Fix invalidates from off-screen plugins on the Mac.

BUG=20234
TEST=Flash plugins that start offscreen should look correct when scrolled into view.

Review URL: http://codereview.chromium.org/173552

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@24621 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed