Check for identity before doing matrix math in more places in gfx::Transform

This should be a good speedup once checking for if a matrix is identity is faster  (i.e. https://codereview.appspot.com/6854113/)- otherwise it's a bit of a wash.

BUG=

Review URL: https://chromiumcodereview.appspot.com/11434027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170485 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed