CSS clip property should not force additional clamping to border box

CSS clip property should not force additional clamping to border box

For a composited layer computing its bounds, there is a code path that
clamps a layer's cliprect to the corresponding element's border box.
However, this is incorrect, since a CSS clip may have valid bounds that
include things outside the border box. So, that clamping should only occur
if there is an overflow clip.

BUG=246728
R=jchaffraix@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=152919

[shawnsingh, 2013-06-21 22:37:26]

PTAL.  This patch is covered by the existing test,
compositing/geometry/clip.html, which previously had an incorrect baseline.  The
other tests needed to be adjusted since they had a CSS clip property that
extended outside the border box, but their behavior does not change at all (and
png expectations on those tests remain the same).

Thanks!

[Julien - ping for review, 2013-06-21 23:47:14]

lgtm, assuming the bots are passing.

[shawnsingh, 2013-06-22 04:24:08]

Committed patchset #2 manually as r152919 (presubmit successful).