Issue #2073 - m-c 523950: Discard decoded frames of very large GIF animations (squashed)

Controlled by image.animated.decode-on-demand.threshold-kb, default 256MB

Includes squashed bugfixes/regressions:
 - m-c 1444537: Shutting down the decode pool should make animated decoders bail early
 - m-c 1628606: Make sure to mark the surface cache entry available before sending the frame complete notification
 - m-c 1502275: Skip recreating the decoder after redecode errors if an animated image is reset
 - m-c 1443232: Don't insert frames into our AnimationFrameBuffer that we consider in error and unusable

image/Decoder.cpp

@@ -36,6 +36,7 @@ Decoder::Decoder(RasterImage* aImage)
   , mHaveExplicitOutputSize(false)
   , mInFrame(false)
   , mFinishedNewFrame(false)
+  , mHasFrameToTake(false)
   , mReachedTerminalState(false)
   , mDecodeDone(false)
   , mError(false)
@@ -254,6 +255,8 @@ Decoder::AllocateFrame(const gfx::IntSize& aOutputSize,
                                         mCurrentFrame.get());
 
   if (mCurrentFrame) {
+    mHasFrameToTake = true;
+
     // Gather the raw pointers the decoders will use.
     mCurrentFrame->GetImageData(&mImageData, &mImageDataLength);
     mCurrentFrame->GetPaletteData(&mColormap, &mColormapSize);
@@ -474,6 +477,7 @@ Decoder::PostError()
     mCurrentFrame->Abort();
     mInFrame = false;
     --mFrameCount;
+    mHasFrameToTake = false;
   }
 }