Mypal/dom/base/ImportManager.cpp

748 lines
23 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "ImportManager.h"
#include "mozilla/dom/ScriptLoader.h"
#include "mozilla/EventListenerManager.h"
#include "HTMLLinkElement.h"
#include "nsContentPolicyUtils.h"
#include "nsContentUtils.h"
#include "nsIChannel.h"
#include "nsIContentPolicy.h"
#include "nsIContentSecurityPolicy.h"
#include "nsIDocument.h"
#include "nsIDOMDocument.h"
#include "nsIDOMEvent.h"
#include "nsIPrincipal.h"
#include "nsIScriptObjectPrincipal.h"
#include "nsNetUtil.h"
//-----------------------------------------------------------------------------
// AutoError
//-----------------------------------------------------------------------------
class AutoError {
public:
explicit AutoError(mozilla::dom::ImportLoader* loader, bool scriptsBlocked = true)
: mLoader(loader)
, mPassed(false)
, mScriptsBlocked(scriptsBlocked)
{}
~AutoError()
{
if (!mPassed) {
mLoader->Error(mScriptsBlocked);
}
}
void Pass() { mPassed = true; }
private:
mozilla::dom::ImportLoader* mLoader;
bool mPassed;
bool mScriptsBlocked;
};
namespace mozilla {
namespace dom {
//-----------------------------------------------------------------------------
// ImportLoader::Updater
//-----------------------------------------------------------------------------
void
ImportLoader::Updater::GetReferrerChain(nsINode* aNode,
nsTArray<nsINode*>& aResult)
{
// We fill up the array backward. First the last link: aNode.
MOZ_ASSERT(mLoader->mLinks.Contains(aNode));
aResult.AppendElement(aNode);
nsINode* node = aNode;
RefPtr<ImportManager> manager = mLoader->Manager();
for (ImportLoader* referrersLoader = manager->Find(node->OwnerDoc());
referrersLoader;
referrersLoader = manager->Find(node->OwnerDoc()))
{
// Then walking up the main referrer chain and append each link
// to the array.
node = referrersLoader->GetMainReferrer();
MOZ_ASSERT(node);
aResult.AppendElement(node);
}
// The reversed order is more useful for consumers.
// XXX: This should probably go to nsTArray or some generic utility
// lib for our containers that we don't have... I would really like to
// get rid of this part...
uint32_t l = aResult.Length();
for (uint32_t i = 0; i < l / 2; i++) {
Swap(aResult[i], aResult[l - i - 1]);
}
}
bool
ImportLoader::Updater::ShouldUpdate(nsTArray<nsINode*>& aNewPath)
{
if (mLoader->Manager()->GetNearestPredecessor(mLoader->GetMainReferrer()) !=
mLoader->mBlockingPredecessor) {
return true;
}
// Let's walk down on the main referrer chains of both the current main and
// the new link, and find the last pair of links that are from the same
// document. This is the junction point between the two referrer chain. Their
// order in the subimport list of that document will determine if we have to
// update the spanning tree or this new edge changes nothing in the script
// execution order.
nsTArray<nsINode*> oldPath;
GetReferrerChain(mLoader->mLinks[mLoader->mMainReferrer], oldPath);
uint32_t max = std::min(oldPath.Length(), aNewPath.Length());
MOZ_ASSERT(max > 0);
uint32_t lastCommonImportAncestor = 0;
for (uint32_t i = 0;
i < max && oldPath[i]->OwnerDoc() == aNewPath[i]->OwnerDoc();
i++)
{
lastCommonImportAncestor = i;
}
MOZ_ASSERT(lastCommonImportAncestor < max);
nsINode* oldLink = oldPath[lastCommonImportAncestor];
nsINode* newLink = aNewPath[lastCommonImportAncestor];
if ((lastCommonImportAncestor == max - 1) &&
newLink == oldLink ) {
// If one chain contains the other entirely, then this is a simple cycle,
// nothing to be done here.
MOZ_ASSERT(oldPath.Length() != aNewPath.Length(),
"This would mean that new link == main referrer link");
return false;
}
MOZ_ASSERT(aNewPath != oldPath,
"How could this happen?");
nsIDocument* doc = oldLink->OwnerDoc();
MOZ_ASSERT(doc->HasSubImportLink(newLink));
MOZ_ASSERT(doc->HasSubImportLink(oldLink));
return doc->IndexOfSubImportLink(newLink) < doc->IndexOfSubImportLink(oldLink);
}
void
ImportLoader::Updater::UpdateMainReferrer(uint32_t aNewIdx)
{
MOZ_ASSERT(aNewIdx < mLoader->mLinks.Length());
nsINode* newMainReferrer = mLoader->mLinks[aNewIdx];
// This new link means we have to execute our scripts sooner...
// Let's make sure that unblocking a loader does not trigger a script execution.
// So we start with placing the new blockers and only then will we remove any
// blockers.
if (mLoader->IsBlocking()) {
// Our import parent is changed, let's block the new one and later unblock
// the old one.
newMainReferrer->OwnerDoc()->
ScriptLoader()->AddParserBlockingScriptExecutionBlocker();
newMainReferrer->OwnerDoc()->BlockDOMContentLoaded();
}
if (mLoader->mDocument) {
// Our nearest predecessor has changed. So let's add the ScriptLoader to the
// new one if there is any. And remove it from the old one.
RefPtr<ImportManager> manager = mLoader->Manager();
ScriptLoader* loader = mLoader->mDocument->ScriptLoader();
ImportLoader*& pred = mLoader->mBlockingPredecessor;
ImportLoader* newPred = manager->GetNearestPredecessor(newMainReferrer);
if (pred) {
if (newPred) {
newPred->AddBlockedScriptLoader(loader);
}
pred->RemoveBlockedScriptLoader(loader);
}
}
if (mLoader->IsBlocking()) {
mLoader->mImportParent->
ScriptLoader()->RemoveParserBlockingScriptExecutionBlocker();
mLoader->mImportParent->UnblockDOMContentLoaded();
}
// Finally update mMainReferrer to point to the newly added link.
mLoader->mMainReferrer = aNewIdx;
mLoader->mImportParent = newMainReferrer->OwnerDoc();
}
nsINode*
ImportLoader::Updater::NextDependant(nsINode* aCurrentLink,
nsTArray<nsINode*>& aPath,
NodeTable& aVisitedNodes, bool aSkipChildren)
{
// Depth first graph traversal.
if (!aSkipChildren) {
// "first child"
ImportLoader* loader = mLoader->Manager()->Find(aCurrentLink);
if (loader && loader->GetDocument()) {
nsINode* firstSubImport = loader->GetDocument()->GetSubImportLink(0);
if (firstSubImport && !aVisitedNodes.Contains(firstSubImport)) {
aPath.AppendElement(aCurrentLink);
aVisitedNodes.PutEntry(firstSubImport);
return firstSubImport;
}
}
}
aPath.AppendElement(aCurrentLink);
// "(parent's) next sibling"
while(aPath.Length() > 1) {
aCurrentLink = aPath[aPath.Length() - 1];
aPath.RemoveElementAt(aPath.Length() - 1);
// Let's find the next "sibling"
ImportLoader* loader = mLoader->Manager()->Find(aCurrentLink->OwnerDoc());
MOZ_ASSERT(loader && loader->GetDocument(), "How can this happend?");
nsIDocument* doc = loader->GetDocument();
MOZ_ASSERT(doc->HasSubImportLink(aCurrentLink));
uint32_t idx = doc->IndexOfSubImportLink(aCurrentLink);
nsINode* next = doc->GetSubImportLink(idx + 1);
if (next) {
// Note: If we found an already visited link that means the parent links has
// closed the circle it's always the "first child" section that should find
// the first already visited node. Let's just assert that.
MOZ_ASSERT(!aVisitedNodes.Contains(next));
aVisitedNodes.PutEntry(next);
return next;
}
}
return nullptr;
}
void
ImportLoader::Updater::UpdateDependants(nsINode* aNode,
nsTArray<nsINode*>& aPath)
{
NodeTable visitedNodes;
nsINode* current = aNode;
uint32_t initialLength = aPath.Length();
bool neededUpdate = true;
while ((current = NextDependant(current, aPath, visitedNodes, !neededUpdate))) {
if (!current || aPath.Length() <= initialLength) {
break;
}
ImportLoader* loader = mLoader->Manager()->Find(current);
if (!loader) {
continue;
}
Updater& updater = loader->mUpdater;
neededUpdate = updater.ShouldUpdate(aPath);
if (neededUpdate) {
updater.UpdateMainReferrer(loader->mLinks.IndexOf(current));
}
}
}
void
ImportLoader::Updater::UpdateSpanningTree(nsINode* aNode)
{
if (mLoader->mReady || mLoader->mStopped) {
// Scripts already executed, nothing to be done here.
return;
}
if (mLoader->mLinks.Length() == 1) {
// If this is the first referrer, let's mark it.
mLoader->mMainReferrer = 0;
return;
}
nsTArray<nsINode*> newReferrerChain;
GetReferrerChain(aNode, newReferrerChain);
if (ShouldUpdate(newReferrerChain)) {
UpdateMainReferrer(mLoader->mLinks.Length() - 1);
UpdateDependants(aNode, newReferrerChain);
}
}
//-----------------------------------------------------------------------------
// ImportLoader
//-----------------------------------------------------------------------------
NS_INTERFACE_MAP_BEGIN(ImportLoader)
NS_INTERFACE_MAP_ENTRY(nsIStreamListener)
NS_INTERFACE_MAP_ENTRY(nsIRequestObserver)
NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(ImportLoader)
NS_INTERFACE_MAP_END
NS_IMPL_CYCLE_COLLECTING_ADDREF(ImportLoader)
NS_IMPL_CYCLE_COLLECTING_RELEASE(ImportLoader)
NS_IMPL_CYCLE_COLLECTION(ImportLoader,
mDocument,
mImportParent,
mLinks)
ImportLoader::ImportLoader(nsIURI* aURI, nsIDocument* aImportParent)
: mURI(aURI)
, mImportParent(aImportParent)
, mBlockingPredecessor(nullptr)
, mReady(false)
, mStopped(false)
, mBlockingScripts(false)
, mUpdater(this)
{
}
void
ImportLoader::BlockScripts()
{
MOZ_ASSERT(!mBlockingScripts);
mImportParent->ScriptLoader()->AddParserBlockingScriptExecutionBlocker();
mImportParent->BlockDOMContentLoaded();
mBlockingScripts = true;
}
void
ImportLoader::UnblockScripts()
{
MOZ_ASSERT(mBlockingScripts);
mImportParent->ScriptLoader()->RemoveParserBlockingScriptExecutionBlocker();
mImportParent->UnblockDOMContentLoaded();
for (uint32_t i = 0; i < mBlockedScriptLoaders.Length(); i++) {
mBlockedScriptLoaders[i]->RemoveParserBlockingScriptExecutionBlocker();
}
mBlockedScriptLoaders.Clear();
mBlockingScripts = false;
}
void
ImportLoader::SetBlockingPredecessor(ImportLoader* aLoader)
{
mBlockingPredecessor = aLoader;
}
void
ImportLoader::DispatchEventIfFinished(nsINode* aNode)
{
MOZ_ASSERT(!(mReady && mStopped));
if (mReady) {
DispatchLoadEvent(aNode);
}
if (mStopped) {
DispatchErrorEvent(aNode);
}
}
void
ImportLoader::AddBlockedScriptLoader(ScriptLoader* aScriptLoader)
{
if (mBlockedScriptLoaders.Contains(aScriptLoader)) {
return;
}
aScriptLoader->AddParserBlockingScriptExecutionBlocker();
// Let's keep track of the pending script loaders.
mBlockedScriptLoaders.AppendElement(aScriptLoader);
}
bool
ImportLoader::RemoveBlockedScriptLoader(ScriptLoader* aScriptLoader)
{
aScriptLoader->RemoveParserBlockingScriptExecutionBlocker();
return mBlockedScriptLoaders.RemoveElement(aScriptLoader);
}
void
ImportLoader::AddLinkElement(nsINode* aNode)
{
// If a new link element is added to the import tree that
// refers to an import that is already finished loading or
// stopped trying, we need to fire the corresponding event
// on it.
mLinks.AppendElement(aNode);
mUpdater.UpdateSpanningTree(aNode);
DispatchEventIfFinished(aNode);
}
void
ImportLoader::RemoveLinkElement(nsINode* aNode)
{
mLinks.RemoveElement(aNode);
}
// Events has to be fired with a script runner, so mImport can
// be set on the link element before the load event is fired even
// if ImportLoader::Get returns an already loaded import and we
// fire the load event immediately on the new referring link element.
class AsyncEvent : public Runnable {
public:
AsyncEvent(nsINode* aNode, bool aSuccess)
: mNode(aNode)
, mSuccess(aSuccess)
{
MOZ_ASSERT(mNode);
}
NS_IMETHOD Run() override {
return nsContentUtils::DispatchTrustedEvent(mNode->OwnerDoc(),
mNode,
mSuccess ? NS_LITERAL_STRING("load")
: NS_LITERAL_STRING("error"),
/* aCanBubble = */ false,
/* aCancelable = */ false);
}
private:
nsCOMPtr<nsINode> mNode;
bool mSuccess;
};
void
ImportLoader::DispatchErrorEvent(nsINode* aNode)
{
nsContentUtils::AddScriptRunner(new AsyncEvent(aNode, /* aSuccess = */ false));
}
void
ImportLoader::DispatchLoadEvent(nsINode* aNode)
{
nsContentUtils::AddScriptRunner(new AsyncEvent(aNode, /* aSuccess = */ true));
}
void
ImportLoader::Done()
{
mReady = true;
uint32_t l = mLinks.Length();
for (uint32_t i = 0; i < l; i++) {
DispatchLoadEvent(mLinks[i]);
}
UnblockScripts();
ReleaseResources();
}
void
ImportLoader::Error(bool aUnblockScripts)
{
mDocument = nullptr;
mStopped = true;
uint32_t l = mLinks.Length();
for (uint32_t i = 0; i < l; i++) {
DispatchErrorEvent(mLinks[i]);
}
if (aUnblockScripts) {
UnblockScripts();
}
ReleaseResources();
}
// Release all the resources we don't need after there is no more
// data available on the channel, and the parser is done.
void ImportLoader::ReleaseResources()
{
mParserStreamListener = nullptr;
mImportParent = nullptr;
}
nsIPrincipal*
ImportLoader::Principal()
{
MOZ_ASSERT(mImportParent);
nsCOMPtr<nsIDocument> master = mImportParent->MasterDocument();
nsCOMPtr<nsIScriptObjectPrincipal> sop = do_QueryInterface(master);
MOZ_ASSERT(sop);
return sop->GetPrincipal();
}
void
ImportLoader::Open()
{
AutoError ae(this, false);
nsCOMPtr<nsILoadGroup> loadGroup =
mImportParent->MasterDocument()->GetDocumentLoadGroup();
nsCOMPtr<nsIChannel> channel;
nsresult rv = NS_NewChannel(getter_AddRefs(channel),
mURI,
mImportParent,
nsILoadInfo::SEC_REQUIRE_CORS_DATA_INHERITS,
nsIContentPolicy::TYPE_SUBDOCUMENT,
loadGroup,
nullptr, // aCallbacks
nsIRequest::LOAD_BACKGROUND);
NS_ENSURE_SUCCESS_VOID(rv);
rv = channel->AsyncOpen2(this);
NS_ENSURE_SUCCESS_VOID(rv);
BlockScripts();
ae.Pass();
}
NS_IMETHODIMP
ImportLoader::OnDataAvailable(nsIRequest* aRequest,
nsISupports* aContext,
nsIInputStream* aStream,
uint64_t aOffset,
uint32_t aCount)
{
MOZ_ASSERT(mParserStreamListener);
AutoError ae(this);
nsresult rv;
nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest, &rv);
NS_ENSURE_SUCCESS(rv, rv);
rv = mParserStreamListener->OnDataAvailable(channel, aContext,
aStream, aOffset,
aCount);
NS_ENSURE_SUCCESS(rv, rv);
ae.Pass();
return rv;
}
NS_IMETHODIMP
ImportLoader::HandleEvent(nsIDOMEvent *aEvent)
{
#ifdef DEBUG
nsAutoString type;
aEvent->GetType(type);
MOZ_ASSERT(type.EqualsLiteral("DOMContentLoaded"));
#endif
Done();
return NS_OK;
}
NS_IMETHODIMP
ImportLoader::OnStopRequest(nsIRequest* aRequest,
nsISupports* aContext,
nsresult aStatus)
{
// OnStartRequest throws a special error code to let us know that we
// shouldn't do anything else.
if (aStatus == NS_ERROR_DOM_ABORT_ERR) {
// We failed in OnStartRequest, nothing more to do (we've already
// dispatched an error event) just return here.
MOZ_ASSERT(mStopped);
return NS_OK;
}
if (mParserStreamListener) {
mParserStreamListener->OnStopRequest(aRequest, aContext, aStatus);
}
if (!mDocument) {
// If at this point we don't have a document, then the error was
// already reported.
return NS_ERROR_DOM_ABORT_ERR;
}
nsCOMPtr<EventTarget> eventTarget = do_QueryInterface(mDocument);
EventListenerManager* manager = eventTarget->GetOrCreateListenerManager();
manager->AddEventListenerByType(this,
NS_LITERAL_STRING("DOMContentLoaded"),
TrustedEventsAtSystemGroupBubble());
return NS_OK;
}
NS_IMETHODIMP
ImportLoader::OnStartRequest(nsIRequest* aRequest, nsISupports* aContext)
{
AutoError ae(this);
nsIPrincipal* principal = Principal();
nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
if (!channel) {
return NS_ERROR_DOM_ABORT_ERR;
}
if (nsContentUtils::IsSystemPrincipal(principal)) {
// We should never import non-system documents and run their scripts with system principal!
nsCOMPtr<nsIPrincipal> channelPrincipal;
nsContentUtils::GetSecurityManager()->GetChannelResultPrincipal(channel,
getter_AddRefs(channelPrincipal));
if (!nsContentUtils::IsSystemPrincipal(channelPrincipal)) {
return NS_ERROR_FAILURE;
}
}
channel->SetOwner(principal);
nsAutoCString type;
channel->GetContentType(type);
if (!type.EqualsLiteral("text/html")) {
NS_WARNING("ImportLoader wrong content type");
return NS_ERROR_DOM_ABORT_ERR;
}
// The scope object is same for all the imports in an import tree,
// let's get it form the import parent.
nsCOMPtr<nsIGlobalObject> global = mImportParent->GetScopeObject();
nsCOMPtr<nsIDOMDocument> importDoc;
nsCOMPtr<nsIURI> baseURI = mImportParent->GetBaseURI();
const nsAString& emptyStr = EmptyString();
nsresult rv = NS_NewDOMDocument(getter_AddRefs(importDoc),
emptyStr, emptyStr, nullptr, mURI,
baseURI, principal, false, global,
DocumentFlavorHTML);
NS_ENSURE_SUCCESS(rv, NS_ERROR_DOM_ABORT_ERR);
// The imported document must know which master document it belongs to.
mDocument = do_QueryInterface(importDoc);
nsCOMPtr<nsIDocument> master = mImportParent->MasterDocument();
mDocument->SetMasterDocument(master);
// We want to inherit the sandbox flags and fullscreen enabled flag
// from the master document.
mDocument->SetSandboxFlags(master->GetSandboxFlags());
// We have to connect the blank document we created with the channel we opened,
// and create its own LoadGroup for it.
nsCOMPtr<nsIStreamListener> listener;
nsCOMPtr<nsILoadGroup> loadGroup;
channel->GetLoadGroup(getter_AddRefs(loadGroup));
nsCOMPtr<nsILoadGroup> newLoadGroup = do_CreateInstance(NS_LOADGROUP_CONTRACTID);
NS_ENSURE_TRUE(newLoadGroup, NS_ERROR_OUT_OF_MEMORY);
newLoadGroup->SetLoadGroup(loadGroup);
rv = mDocument->StartDocumentLoad("import", channel, newLoadGroup,
nullptr, getter_AddRefs(listener),
true);
NS_ENSURE_SUCCESS(rv, NS_ERROR_DOM_ABORT_ERR);
nsCOMPtr<nsIURI> originalURI;
rv = channel->GetOriginalURI(getter_AddRefs(originalURI));
NS_ENSURE_SUCCESS(rv, NS_ERROR_DOM_ABORT_ERR);
nsCOMPtr<nsIURI> URI;
rv = channel->GetURI(getter_AddRefs(URI));
NS_ENSURE_SUCCESS(rv, NS_ERROR_DOM_ABORT_ERR);
MOZ_ASSERT(URI, "URI of a channel should never be null");
bool equals;
rv = URI->Equals(originalURI, &equals);
NS_ENSURE_SUCCESS(rv, NS_ERROR_DOM_ABORT_ERR);
if (!equals) {
// In case of a redirection we must add the new URI to the import map.
Manager()->AddLoaderWithNewURI(this, URI);
}
// Let's start the parser.
mParserStreamListener = listener;
rv = listener->OnStartRequest(aRequest, aContext);
NS_ENSURE_SUCCESS(rv, NS_ERROR_DOM_ABORT_ERR);
ae.Pass();
return NS_OK;
}
//-----------------------------------------------------------------------------
// ImportManager
//-----------------------------------------------------------------------------
NS_IMPL_CYCLE_COLLECTION(ImportManager,
mImports)
NS_INTERFACE_MAP_BEGIN(ImportManager)
NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(ImportManager)
NS_INTERFACE_MAP_END
NS_IMPL_CYCLE_COLLECTING_ADDREF(ImportManager)
NS_IMPL_CYCLE_COLLECTING_RELEASE(ImportManager)
already_AddRefed<ImportLoader>
ImportManager::Get(nsIURI* aURI, nsINode* aNode, nsIDocument* aOrigDocument)
{
// Check if we have a loader for that URI, if not create one,
// and start it up.
RefPtr<ImportLoader> loader;
mImports.Get(aURI, getter_AddRefs(loader));
bool needToStart = false;
if (!loader) {
loader = new ImportLoader(aURI, aOrigDocument);
mImports.Put(aURI, loader);
needToStart = true;
}
MOZ_ASSERT(loader);
// Let's keep track of the sub imports links in each document. It will
// be used later for scrip execution order calculation. (see UpdateSpanningTree)
// NOTE: removing and adding back the link to the tree somewhere else will
// NOT have an effect on script execution order.
if (!aOrigDocument->HasSubImportLink(aNode)) {
aOrigDocument->AddSubImportLink(aNode);
}
loader->AddLinkElement(aNode);
if (needToStart) {
loader->Open();
}
return loader.forget();
}
ImportLoader*
ImportManager::Find(nsIDocument* aImport)
{
return mImports.GetWeak(aImport->GetDocumentURIObject());
}
ImportLoader*
ImportManager::Find(nsINode* aLink)
{
HTMLLinkElement* linkElement = static_cast<HTMLLinkElement*>(aLink);
nsCOMPtr<nsIURI> uri = linkElement->GetHrefURI();
return mImports.GetWeak(uri);
}
void
ImportManager::AddLoaderWithNewURI(ImportLoader* aLoader, nsIURI* aNewURI)
{
mImports.Put(aNewURI, aLoader);
}
ImportLoader* ImportManager::GetNearestPredecessor(nsINode* aNode)
{
// Return the previous link if there is any in the same document.
nsIDocument* doc = aNode->OwnerDoc();
int32_t idx = doc->IndexOfSubImportLink(aNode);
MOZ_ASSERT(idx != -1, "aNode must be a sub import link of its owner document");
for (; idx > 0; idx--) {
HTMLLinkElement* link =
static_cast<HTMLLinkElement*>(doc->GetSubImportLink(idx - 1));
nsCOMPtr<nsIURI> uri = link->GetHrefURI();
RefPtr<ImportLoader> ret;
mImports.Get(uri, getter_AddRefs(ret));
// Only main referrer links are interesting.
if (ret->GetMainReferrer() == link) {
return ret;
}
}
if (idx == 0) {
if (doc->IsMasterDocument()) {
// If there is no previous one, and it was the master document, then
// there is no predecessor.
return nullptr;
}
// Else we find the main referrer of the import parent of the link's document.
// And do a recursion.
ImportLoader* owner = Find(doc);
MOZ_ASSERT(owner);
nsCOMPtr<nsINode> mainReferrer = owner->GetMainReferrer();
return GetNearestPredecessor(mainReferrer);
}
return nullptr;
}
} // namespace dom
} // namespace mozilla