diff --git a/dom/canvas/WebGLContext.h b/dom/canvas/WebGLContext.h
index 8a20237ff..0510e6898 100644
--- a/dom/canvas/WebGLContext.h
+++ b/dom/canvas/WebGLContext.h
@@ -20,6 +20,7 @@
 #include "mozilla/gfx/2D.h"
 #include "mozilla/LinkedList.h"
 #include "mozilla/UniquePtr.h"
+#include "mozilla/WeakPtr.h"
 #include "nsCycleCollectionNoteChild.h"
 #include "nsICanvasRenderingContextInternal.h"
 #include "nsLayoutUtils.h"
@@ -299,6 +300,7 @@ class WebGLContext
     , public WebGLContextUnchecked
     , public WebGLRectangleObject
     , public nsWrapperCache
+    , public SupportsWeakPtr<WebGLContext>
 {
     friend class ScopedDrawHelper;
     friend class ScopedDrawWithTransformFeedback;
@@ -342,6 +344,7 @@ public:
 
     NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(WebGLContext,
                                                            nsIDOMWebGLRenderingContext)
+    MOZ_DECLARE_WEAKREFERENCE_TYPENAME(WebGLContext)
 
     virtual JSObject* WrapObject(JSContext* cx, JS::Handle<JSObject*> givenProto) override = 0;
 
diff --git a/dom/canvas/WebGLExtensionDebugShaders.cpp b/dom/canvas/WebGLExtensionDebugShaders.cpp
index 75880465e..8399aeb95 100644
--- a/dom/canvas/WebGLExtensionDebugShaders.cpp
+++ b/dom/canvas/WebGLExtensionDebugShaders.cpp
@@ -29,15 +29,10 @@ WebGLExtensionDebugShaders::GetTranslatedShaderSource(const WebGLShader& shader,
 {
     retval.SetIsVoid(true);
 
-    if (mIsLost) {
-        mContext->ErrorInvalidOperation("%s: Extension is lost.",
-                                        "getTranslatedShaderSource");
+    if (mIsLost || !mContext) {
         return;
     }
 
-    if (mContext->IsContextLost())
-        return;
-
     if (!mContext->ValidateObject("getShaderTranslatedSource: shader", shader))
         return;
 
diff --git a/dom/canvas/WebGLExtensionDisjointTimerQuery.cpp b/dom/canvas/WebGLExtensionDisjointTimerQuery.cpp
index e2e34f14e..da76eeb2d 100644
--- a/dom/canvas/WebGLExtensionDisjointTimerQuery.cpp
+++ b/dom/canvas/WebGLExtensionDisjointTimerQuery.cpp
@@ -40,8 +40,10 @@ void
 WebGLExtensionDisjointTimerQuery::DeleteQueryEXT(WebGLQuery* query) const
 {
     const char funcName[] = "deleteQueryEXT";
-    if (mIsLost)
-        return;
+
+    if (mIsLost || !mContext) {
+      return;
+    }
 
     mContext->DeleteQuery(query, funcName);
 }
@@ -50,8 +52,10 @@ bool
 WebGLExtensionDisjointTimerQuery::IsQueryEXT(const WebGLQuery* query) const
 {
     const char funcName[] = "isQueryEXT";
-    if (mIsLost)
-        return false;
+
+    if (mIsLost || !mContext) {
+      return false;
+    }
 
     return mContext->IsQuery(query, funcName);
 }
@@ -60,8 +64,10 @@ void
 WebGLExtensionDisjointTimerQuery::BeginQueryEXT(GLenum target, WebGLQuery& query) const
 {
     const char funcName[] = "beginQueryEXT";
-    if (mIsLost)
-        return;
+
+    if (mIsLost || !mContext) {
+      return;
+    }
 
     mContext->BeginQuery(target, query, funcName);
 }
@@ -70,8 +76,10 @@ void
 WebGLExtensionDisjointTimerQuery::EndQueryEXT(GLenum target) const
 {
     const char funcName[] = "endQueryEXT";
-    if (mIsLost)
-        return;
+
+    if (mIsLost || !mContext) {
+      return;
+    }
 
     mContext->EndQuery(target, funcName);
 }
@@ -80,8 +88,10 @@ void
 WebGLExtensionDisjointTimerQuery::QueryCounterEXT(WebGLQuery& query, GLenum target) const
 {
     const char funcName[] = "queryCounterEXT";
-    if (mIsLost)
-        return;
+
+    if (mIsLost || !mContext) {
+      return;
+    }
 
     if (!mContext->ValidateObject(funcName, query))
         return;
@@ -95,8 +105,10 @@ WebGLExtensionDisjointTimerQuery::GetQueryEXT(JSContext* cx, GLenum target, GLen
 {
     const char funcName[] = "getQueryEXT";
     retval.setNull();
-    if (mIsLost)
-        return;
+
+    if (mIsLost || !mContext) {
+      return;
+    }
 
     mContext->GetQuery(cx, target, pname, retval, funcName);
 }
@@ -108,8 +120,10 @@ WebGLExtensionDisjointTimerQuery::GetQueryObjectEXT(JSContext* cx,
 {
     const char funcName[] = "getQueryObjectEXT";
     retval.setNull();
-    if (mIsLost)
-        return;
+
+    if (mIsLost || !mContext) {
+      return;
+    }
 
     mContext->GetQueryParameter(cx, query, pname, retval, funcName);
 }
diff --git a/dom/canvas/WebGLExtensionDrawBuffers.cpp b/dom/canvas/WebGLExtensionDrawBuffers.cpp
index 27aa76cc7..6f386621f 100644
--- a/dom/canvas/WebGLExtensionDrawBuffers.cpp
+++ b/dom/canvas/WebGLExtensionDrawBuffers.cpp
@@ -36,7 +36,9 @@ void
 WebGLExtensionDrawBuffers::DrawBuffersWEBGL(const dom::Sequence<GLenum>& buffers)
 {
     if (mIsLost) {
-        mContext->ErrorInvalidOperation("drawBuffersWEBGL: Extension is lost.");
+        if (mContext) {
+            mContext->ErrorInvalidOperation("drawBuffersWEBGL: Extension is lost.");
+        }
         return;
     }
 
diff --git a/dom/canvas/WebGLExtensionInstancedArrays.cpp b/dom/canvas/WebGLExtensionInstancedArrays.cpp
index 10d0533fe..22b3ec12c 100644
--- a/dom/canvas/WebGLExtensionInstancedArrays.cpp
+++ b/dom/canvas/WebGLExtensionInstancedArrays.cpp
@@ -28,8 +28,10 @@ WebGLExtensionInstancedArrays::DrawArraysInstancedANGLE(GLenum mode,
                                                         GLsizei primcount)
 {
     if (mIsLost) {
-        mContext->ErrorInvalidOperation("%s: Extension is lost.",
-                                        "drawArraysInstancedANGLE");
+        if (mContext) {
+            mContext->ErrorInvalidOperation("%s: Extension is lost.",
+                                            "drawArraysInstancedANGLE");
+        }
         return;
     }
 
@@ -44,8 +46,10 @@ WebGLExtensionInstancedArrays::DrawElementsInstancedANGLE(GLenum mode,
                                                           GLsizei primcount)
 {
     if (mIsLost) {
-        mContext->ErrorInvalidOperation("%s: Extension is lost.",
-                                        "drawElementsInstancedANGLE");
+        if (mContext) {
+            mContext->ErrorInvalidOperation("%s: Extension is lost.",
+                                            "drawElementsInstancedANGLE");
+        }
         return;
     }
 
@@ -57,8 +61,10 @@ WebGLExtensionInstancedArrays::VertexAttribDivisorANGLE(GLuint index,
                                                         GLuint divisor)
 {
     if (mIsLost) {
-        mContext->ErrorInvalidOperation("%s: Extension is lost.",
-                                        "vertexAttribDivisorANGLE");
+        if (mContext) {
+            mContext->ErrorInvalidOperation("%s: Extension is lost.",
+                                            "vertexAttribDivisorANGLE");
+        }
         return;
     }
 
diff --git a/dom/canvas/WebGLExtensionLoseContext.cpp b/dom/canvas/WebGLExtensionLoseContext.cpp
index 020731e63..41f1633d8 100644
--- a/dom/canvas/WebGLExtensionLoseContext.cpp
+++ b/dom/canvas/WebGLExtensionLoseContext.cpp
@@ -22,12 +22,14 @@ WebGLExtensionLoseContext::~WebGLExtensionLoseContext()
 void
 WebGLExtensionLoseContext::LoseContext()
 {
+    if (!mContext) return;
     mContext->LoseContext();
 }
 
 void
 WebGLExtensionLoseContext::RestoreContext()
 {
+    if (!mContext) return;
     mContext->RestoreContext();
 }
 
diff --git a/dom/canvas/WebGLExtensionVertexArray.cpp b/dom/canvas/WebGLExtensionVertexArray.cpp
index 0984582f5..39aa96801 100644
--- a/dom/canvas/WebGLExtensionVertexArray.cpp
+++ b/dom/canvas/WebGLExtensionVertexArray.cpp
@@ -25,7 +25,7 @@ WebGLExtensionVertexArray::~WebGLExtensionVertexArray()
 already_AddRefed<WebGLVertexArray>
 WebGLExtensionVertexArray::CreateVertexArrayOES()
 {
-    if (mIsLost)
+    if (mIsLost || !mContext)
         return nullptr;
 
     return mContext->CreateVertexArray();
@@ -34,7 +34,7 @@ WebGLExtensionVertexArray::CreateVertexArrayOES()
 void
 WebGLExtensionVertexArray::DeleteVertexArrayOES(WebGLVertexArray* array)
 {
-    if (mIsLost)
+    if (mIsLost || !mContext)
         return;
 
     mContext->DeleteVertexArray(array);
@@ -43,7 +43,7 @@ WebGLExtensionVertexArray::DeleteVertexArrayOES(WebGLVertexArray* array)
 bool
 WebGLExtensionVertexArray::IsVertexArrayOES(const WebGLVertexArray* array)
 {
-    if (mIsLost)
+    if (mIsLost || !mContext)
         return false;
 
     return mContext->IsVertexArray(array);
@@ -52,7 +52,7 @@ WebGLExtensionVertexArray::IsVertexArrayOES(const WebGLVertexArray* array)
 void
 WebGLExtensionVertexArray::BindVertexArrayOES(WebGLVertexArray* array)
 {
-    if (mIsLost)
+    if (mIsLost || !mContext)
         return;
 
     mContext->BindVertexArray(array);
diff --git a/dom/canvas/WebGLObjectModel.h b/dom/canvas/WebGLObjectModel.h
index b18b790c0..6371c7b03 100644
--- a/dom/canvas/WebGLObjectModel.h
+++ b/dom/canvas/WebGLObjectModel.h
@@ -6,8 +6,8 @@
 #ifndef WEBGLOBJECTMODEL_H_
 #define WEBGLOBJECTMODEL_H_
 
+#include "mozilla/WeakPtr.h"
 #include "nsCycleCollectionNoteChild.h"
-
 #include "WebGLTypes.h"
 
 namespace mozilla {
@@ -24,7 +24,7 @@ class WebGLContext;
 class WebGLContextBoundObject
 {
 public:
-    WebGLContext* const mContext;
+    const WeakPtr<WebGLContext> mContext;
 private:
     const uint32_t mContextGeneration;