Bug 1414825. Clear mDataWrapper on ImageBitmap::Close because it holds gfx resources alive. r=nical

dom/canvas/ImageBitmap.cpp

@@ -548,6 +548,7 @@ ImageBitmap::Close()
 {
   mData = nullptr;
   mSurface = nullptr;
+  mDataWrapper = nullptr;
   mPictureRect.SetEmpty();
 }
 
@@ -1572,7 +1573,10 @@ ImageBitmapFormat
 ImageBitmap::FindOptimalFormat(const Optional<Sequence<ImageBitmapFormat>>& aPossibleFormats,
                                ErrorResult& aRv)
 {
-  MOZ_ASSERT(mDataWrapper, "No ImageBitmapFormatUtils functionalities.");
+  if (!mDataWrapper) {
+    aRv.Throw(NS_ERROR_NOT_AVAILABLE);
+    return ImageBitmapFormat::EndGuard_;
+  }
 
   ImageBitmapFormat platformFormat = mDataWrapper->GetFormat();
 
@@ -1596,7 +1600,10 @@ ImageBitmap::FindOptimalFormat(const Optional<Sequence<ImageBitmapFormat>>& aPos
 int32_t
 ImageBitmap::MappedDataLength(ImageBitmapFormat aFormat, ErrorResult& aRv)
 {
-  MOZ_ASSERT(mDataWrapper, "No ImageBitmapFormatUtils functionalities.");
+  if (!mDataWrapper) {
+    aRv.Throw(NS_ERROR_NOT_AVAILABLE);
+    return 0;
+  }
 
   if (aFormat == mDataWrapper->GetFormat()) {
     return mDataWrapper->GetBufferLength();
@@ -1632,6 +1639,12 @@ protected:
   {
     ErrorResult error;
 
+    if (!mImageBitmap->mDataWrapper) {
+      error.ThrowWithCustomCleanup(NS_ERROR_NOT_AVAILABLE);
+      mPromise->MaybeReject(error);
+      return;
+    }
+
     // Prepare destination buffer.
     uint8_t* bufferData = nullptr;
     uint32_t bufferLength = 0;
@@ -1784,7 +1797,6 @@ ImageBitmap::MapDataInto(JSContext* aCx,
                          const ArrayBufferViewOrArrayBuffer& aBuffer,
                          int32_t aOffset, ErrorResult& aRv)
 {
-  MOZ_ASSERT(mDataWrapper, "No ImageBitmapFormatUtils functionalities.");
   MOZ_ASSERT(aCx, "No JSContext while calling ImageBitmap::MapDataInto().");
 
   RefPtr<Promise> promise = Promise::Create(mParent, aRv);
@@ -1793,6 +1805,12 @@ ImageBitmap::MapDataInto(JSContext* aCx,
     return nullptr;
   }
 
+  if (!mDataWrapper) {
+    aRv.Throw(NS_ERROR_NOT_AVAILABLE);
+    return promise.forget();
+
+  }
+
   // Check for cases that should throws.
   // Case 1:
   // If image bitmap was cropped to the source rectangle so that it contains any