CSS clip should not be considered when clamping for overflow clip.

CSS clip should not be considered when clamping for overflow clip.

Previous patch in webkit rev 152919 partially fixed this, but skipped one code
path that still needed fixing. These code paths are intended to clamp the
backgroundRect to the borderBox, or a slightly inflated borderBox.  It is
incorrect to trigger those code paths when there is only CSS clip and no
overflow clip.  Fixing this bug also results in a tiny refactor where the CSS
clip if-statement is separated from the overflow clip chunks of code.

BUG=246728
R=esprehn@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=152980

[shawnsingh, 2013-06-25 01:26:46]

PTAL, thanks very much!  Still running tests, but I am optimistic they will
pass.

It looks like the diff recognizes that clip-with-shadow test case was copied
from clip.html test case.  But this is actually a new test that covers the fix
on this patch.

[esprehn, 2013-06-25 01:34:07]

LGTM. Thanks for adding some comments too!

[shawnsingh, 2013-06-25 03:45:06]

Committed patchset #1 manually as r152980 (presubmit successful).