Checking if frame is complete and access duration doesn't need a decode

Source/core/platform/image-decoders/gif/GIFImageDecoder.h

Index: Source/core/platform/image-decoders/gif/GIFImageDecoder.h
diff --git a/Source/core/platform/image-decoders/gif/GIFImageDecoder.h b/Source/core/platform/image-decoders/gif/GIFImageDecoder.h
index f9e1b84d3181aa6c55fbac248eb312e9542b8a14..b1e95fa970bad0d6faf62d48f7cb29988e36df75 100644
--- a/Source/core/platform/image-decoders/gif/GIFImageDecoder.h
+++ b/Source/core/platform/image-decoders/gif/GIFImageDecoder.h
@@ -49,6 +49,8 @@ namespace WebCore {
         virtual size_t frameCount();
         virtual int repetitionCount() const;
         virtual ImageFrame* frameBufferAtIndex(size_t index);
+        virtual bool frameIsCompleteAtIndex(size_t) const;
+        virtual float frameDurationAtIndex(size_t) const;
         // CAUTION: setFailed() deletes |m_reader|.  Be careful to avoid
         // accessing deleted memory, especially when calling this from inside
         // GIFImageReader!