Fixed GPU unit tests on Mac OS X.

 - Fixed remaining issues with signed/unsigned comparisons, linkage of
   constants, and unused variables.
 - Fixed nasty bug where vtbl for GLES2Decoder was changing size during
   compilation, causing bizarre test failures.
 - Cleaned up AppKit warnings about no NSAutoreleasePool being present.

BUG=none
TEST=none (ran GPU unit tests on Mac OS X)

Review URL: http://codereview.chromium.org/594004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@38473 0039d316-1c4b-4281-b951-d872f2087c98
10 files changed