Fix handling of broken GIFs with weird frame sizes

Source/platform/image-decoders/gif/GIFImageDecoderTest.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 481 matching lines @@
     RefPtr<SharedBuffer> data = readFile("/Source/web/tests/data/invalid-disposal-method.gif");
     ASSERT_TRUE(data.get());
     decoder->setData(data.get(), true);
 
     EXPECT_EQ(2u, decoder->frameCount());
     // Disposal method 4 is converted to ImageFrame::DisposeOverwritePrevious.
     EXPECT_EQ(ImageFrame::DisposeOverwritePrevious, decoder->frameBufferAtIndex(0)->disposalMethod());
     // Disposal method 5 is ignored.
     EXPECT_EQ(ImageFrame::DisposeNotSpecified, decoder->frameBufferAtIndex(1)->disposalMethod());
 }
+
+TEST(GIFImageDecoderTest, firstFrameHasGreaterSizeThanScreenSize)
+{
+    RefPtr<SharedBuffer> fullData = readFile("/Source/platform/image-decoders/testing/first-frame-has-greater-size-than-screen-size.gif");

[Stephen White, 2015/01/14 22:17:02]

Not new to this CL, but we should probably shorten these paths or make them
relative to the file somehoow. At a minimum, we should put the common prefix in
a single string at the top of the file, IMHO.

[Alpha Left Google, 2015/01/14 23:14:59]

Done.

+    ASSERT_TRUE(fullData.get());
+
+    OwnPtr<GIFImageDecoder> decoder;
+    IntSize frameSize;
+
+    // Compute hashes when the file is truncated.
+    for (size_t i = 1; i <= fullData->size(); ++i) {
+        decoder = createDecoder();
+        RefPtr<SharedBuffer> data = SharedBuffer::create(fullData->data(), i);
+        decoder->setData(data.get(), i == fullData->size());
+
+        if (decoder->isSizeAvailable() && !frameSize.width() && !frameSize.height()) {
+            frameSize = decoder->decodedSize();
+            continue;
+        }
+
+        ASSERT_EQ(frameSize.width(), decoder->decodedSize().width());
+        ASSERT_EQ(frameSize.height(), decoder->decodedSize().height());
+    }
+}