Don't cache any SkBitmaps in DeferredImageDecoder

Source/platform/blink_platform.gypi

 {
   'includes': [
     'platform_generated.gypi',
   ],
   'variables': {
     'platform_files': [
       'AsyncFileSystemCallbacks.h',
       'CalculationValue.h',
       'CheckedInt.h',
       'Clock.cpp',
@@ skipping 655 matching lines @@
       'graphics/paint/TransformDisplayItem.h',
       'graphics/paint/CompositingDisplayItem.cpp',
       'graphics/paint/CompositingDisplayItem.h',
       'graphics/skia/GaneshUtils.cpp',
       'graphics/skia/GaneshUtils.h',
       'graphics/skia/NativeImageSkia.cpp',
       'graphics/skia/NativeImageSkia.h',
       'graphics/skia/SkSizeHash.h',
       'graphics/skia/SkiaUtils.cpp',
       'graphics/skia/SkiaUtils.h',
+      'image-decoders/ImageAnimation.h',
       'image-decoders/ImageDecoder.cpp',
       'image-decoders/ImageDecoder.h',
       'image-decoders/ImageFrame.cpp',
       'image-decoders/ImageFrame.h',
       'image-decoders/bmp/BMPImageDecoder.cpp',
       'image-decoders/bmp/BMPImageDecoder.h',
       'image-decoders/bmp/BMPImageReader.cpp',
       'image-decoders/bmp/BMPImageReader.h',
       'image-decoders/gif/GIFImageDecoder.cpp',
       'image-decoders/gif/GIFImageDecoder.h',
@@ skipping 301 matching lines @@
       'graphics/ImageLayerChromiumTest.cpp',
       'graphics/test/MockImageDecoder.h',
       'graphics/test/MockWebGraphicsContext3D.h',
       'image-decoders/bmp/BMPImageDecoderTest.cpp',
       'image-decoders/gif/GIFImageDecoderTest.cpp',
       'image-decoders/jpeg/JPEGImageDecoderTest.cpp',
       'image-decoders/webp/WEBPImageDecoderTest.cpp',
     ],
   },
 }