Revert r174436 (Reduce the cost of the n^2 loop in collectTreeBoundaryCrossingRules)

Revert r174436 (Reduce the cost of the n^2 loop in collectTreeBoundaryCrossingRules)

https://src.chromium.org/viewvc/blink?view=rev&revision=174436

r174436 was introduced to improve the performance, but
introduced some regressions for shadow styling.

Added a layout test based on the report in issue 383366
to prevent the same regression again.

BUG=383366, 372083
TEST=pass all layout tests.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=176099

[kochi, 2014-06-13 06:24:42]

Hi Takashi, Elliott,

While looking issue 383366, I found r174436 was causing
the regression.

As the CL looks safe to revert (although performance will
degrade), I think it is better to revert it now, then
work on fixing the CL after M37 is branched.

What do you think?

[hayato, 2014-06-13 06:31:13]

lgtm

[commit-bot: I haz the power, 2014-06-13 06:32:24]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/kochi@chromium.org/323423008/20001

[commit-bot: I haz the power, 2014-06-13 08:40:36]

Change committed as 176099

[esprehn, 2014-06-13 08:57:02]

On 2014/06/13 at 08:40:36, commit-bot wrote:
> Change committed as 176099

Thanks for reverting this. Looks like we need to really fix it for good, hacks
aren't going to work. Also you're amazing for adding a test!