Removing valgrind suppression for issue 303546

Issue 303546 was resolved in Blink with patch:
http://src.chromium.org/viewvc/blink?view=rev&rev=158863

TBR=glider@chromium.org
BUG=303546

Review URL: https://codereview.chromium.org/25619007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227279 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227279