[help] Disable a test on official Mac builder for now.
[help] Disable a test on official Mac builder for now.

TBR=danhn@chromium.org
BUG=118477
TEST=Mac official builder goes green in browser_tests.

Review URL: https://chromiumcodereview.appspot.com/9969090

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@130329 0039d316-1c4b-4281-b951-d872f2087c98

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