Don't crash when an image fails to decode.

Source/platform/graphics/BitmapImage.cpp

 /*
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 352 matching lines @@
     return m_source.frameDurationAtIndex(index);
 }
 
 PassRefPtr<NativeImageSkia> BitmapImage::nativeImageForCurrentFrame()
 {
     return frameAtIndex(currentFrame());
 }
 
 PassRefPtr<Image> BitmapImage::imageForDefaultFrame()
 {
-    if (frameCount() > 1)
+    if (frameCount() > 1 && frameAtIndex(0))
         return BitmapImage::create(frameAtIndex(0));
 
     return Image::imageForDefaultFrame();
 }
 
 bool BitmapImage::frameHasAlphaAtIndex(size_t index)
 {
     if (m_frames.size() <= index)
         return true;
 
@@ skipping 249 matching lines @@
 
     return m_isSolidColor && !m_currentFrame;
 }
 
 Color BitmapImage::solidColor() const
 {
     return m_solidColor;
 }
 
 } // namespace blink