Revert 160993 - Revert 160976 - The center of a rect is x+width/2, y+height/2
If a rect is (0, 0, 5, 5) the center should be 2.5, 2.5, not 2, 2.
Tests:
ui_unittests:RectTest.CenterPoint
ui_unittests:RectTest.CenterPointF
BUG=147395
Review URL: https://chromiumcodereview.appspot.com/
11065050
TBR=danakj@chromium.org
Review URL: https://codereview.chromium.org/
11086037
TBR=cpu@chromium.org
Review URL: https://codereview.chromium.org/
11088048
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@160995 0039d316-1c4b-4281-b951-d872f2087c98