Avoid copying the CachedUAStyle when possible

Avoid copying the CachedUAStyle when possible

1.6% of the overall profile, and 2% of the recalcStyle, in the PeaceKeeper
benchmark is spent inside cacheUserAgentBorderAndBackground() because even
though there is an appearance guard on the constructor, we still run
constructors and destructors for all the members which aren't free since lots
of them have a lot of fields to initialize (ex. FillLayers and BorderData).

This patch moves the check from the constructor of CachedUAStyle into
cacheUserAgentBorderAndBackground() so that we can skip all the
initialization for the common case where the element has no appearance.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=169408

[eseidel, 2014-03-17 17:41:18]

lgtm

[commit-bot: I haz the power, 2014-03-17 17:41:36]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/esprehn@chromium.org/202223002/1

[commit-bot: I haz the power, 2014-03-17 18:03:26]

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

[commit-bot: I haz the power, 2014-03-17 18:03:26]

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

[esprehn, 2014-03-17 18:05:31]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2014-03-17 18:05:35]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/esprehn@chromium.org/202223002/1

[commit-bot: I haz the power, 2014-03-17 18:06:17]

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

[commit-bot: I haz the power, 2014-03-17 18:06:18]

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

[ojan, 2014-03-17 18:59:12]

lgtm

https://codereview.chromium.org/202223002/diff/1/Source/core/css/resolver/Sty...
File Source/core/css/resolver/StyleResolverState.h (right):

https://codereview.chromium.org/202223002/diff/1/Source/core/css/resolver/Sty...
Source/core/css/resolver/StyleResolverState.h:97: void
cacheUserAgentBorderAndBackground()
Nit: this is now kind of big for the header file. Move to the cpp?

[esprehn, 2014-03-17 23:52:23]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2014-03-17 23:52:34]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/esprehn@chromium.org/202223002/1

[commit-bot: I haz the power, 2014-03-18 03:23:17]

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

[commit-bot: I haz the power, 2014-03-18 03:23:17]

Commit queue rejected this change because the description was changed
between the time the change entered the commit queue and the time it
was ready to commit. You can safely check the commit box again.

[esprehn, 2014-03-18 03:32:43]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2014-03-18 03:33:29]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/esprehn@chromium.org/202223002/1

[commit-bot: I haz the power, 2014-03-18 03:36:39]

Change committed as 169408