Don't repaint when setting border or outline 0 with style none

Don't repaint when setting border or outline 0 with style none

We were causing repaints when setting the width of border or outline to
0 on an element that has outline or border style of none because the
internal default width is 3px, even though we compute the width to 0
at layout and paint time.

This patch adds a new method visuallyEqual and uses that when doing the
visualInvalidationDiff to avoid causing repaints when the visual output
would be identical.

It also apparently also reduces the amount of repainting in
fast/repaint/table-collapsed-border.html the table tests, but the visual
output is identical so it appears correct.

BUG=357629
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=170743

[esprehn, 2014-04-02 23:51:14]

I need to figure out how to write a repaint test for this.

[esprehn, 2014-04-03 00:48:04]

Ready for review!

[ojan, 2014-04-03 00:51:05]

lgtm

https://codereview.chromium.org/222473005/diff/40001/LayoutTests/fast/repaint...
File LayoutTests/fast/repaint/border-outline-0.html (right):

https://codereview.chromium.org/222473005/diff/40001/LayoutTests/fast/repaint...
LayoutTests/fast/repaint/border-outline-0.html:16: function repaintTest() {
Should this also test the cases of border-style:hidden?

Also, should there be a test for the case of having a border-image causing a
repaint?

[esprehn, 2014-04-03 01:14:58]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2014-04-03 01:15:05]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/esprehn@chromium.org/222473005/60001

[commit-bot: I haz the power, 2014-04-03 01:50:55]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-04-03 01:50:55]

Try jobs failed on following builders:
  tryserver.blink on linux_blink_rel

[esprehn, 2014-04-03 02:18:27]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2014-04-03 02:18:34]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/esprehn@chromium.org/222473005/160001

[commit-bot: I haz the power, 2014-04-03 02:44:58]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-04-03 02:44:59]

Try jobs failed on following builders:
  tryserver.blink on win_blink_compile_dbg

[esprehn, 2014-04-03 05:57:14]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2014-04-03 05:57:19]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/esprehn@chromium.org/222473005/160001

[commit-bot: I haz the power, 2014-04-03 06:21:34]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-04-03 06:21:35]

Try jobs failed on following builders:
  tryserver.blink on win_blink_compile_dbg

[esprehn, 2014-04-03 06:36:39]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2014-04-03 06:36:44]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/esprehn@chromium.org/222473005/160001

[commit-bot: I haz the power, 2014-04-03 07:01:15]

Change committed as 170743