commit a46d892723fe86a7f49113c46e3c40c2343724ce
author alancutter <alancutter@chromium.org> Wed Jul 06 03:57:05 2016
committer Commit bot <commit-bot@chromium.org> Wed Jul 06 03:59:34 2016
tree 1aa675b38f37563d5668c10333a1e374e978063e
parent 53feaa41b65987c69f54da1152d50f45e04deaac

Avoid touching z-index in StyleAdjuster by using an isStackingContext flag instead

This change moves logic in StyleAdjuster for changing the computed
z-index out into ComputedStyle::updateIsStackingContext().

This ensures we compute and inherit the correct z-index value
almost all of the time (see new test failure expectations).
Also by updating the flag outside of style resolution any new
CSS animations that affect stacking are now accounted for.

This patch is an alternative to https://codereview.chromium.org/2035793007.

BUG=616674, 375982

Review-Url: https://codereview.chromium.org/2047283002
Cr-Commit-Position: refs/heads/master@{#403844}