[OSX] Turn on canvas_skia for OSX

Re-submit of r222192, with fixed tests.

R=asvitkine@chromium.org
BUG=151935

Review URL: https://chromiumcodereview.appspot.com/23604055

git-svn-id: http://src.chromium.org/svn/trunk/src/build@223202 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -655,7 +655,7 @@
         #
         # On Aura, this allows per-tile painting to be used in the browser
         # compositor.
-        ['OS!="mac" and OS!="android"', {
+        ['OS!="android"', {
           'use_canvas_skia%': 1,
         }],