GIFImageDecoder.cpp (which is not used by Safari, but is used by the Cairo port, and is related to the code used by Chromium) has a memory corruption bug with GIFs which insert empty frames, like the one given above.
The fix is to ensure frames get initialized even if we never call haveDecodedRow(). Patch coming shortly.
Created attachment 26066 [details]
Comment on attachment 26066 [details]
Fixed in r39340.