Apply shader short circuit workaround on MacOSX

BUG=307751
TEST=conformance test mentioned in the crbug
R=bajones@chromium.org, kbr@chromium.org

Review URL: https://codereview.chromium.org/27343003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229208 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229208