Web Inspector: [REGRESSION] Slow continuous DOM traversal with Up/Down keys

Web Inspector: [REGRESSION] Slow continuous DOM traversal with Up/Down keys
https://bugs.webkit.org/show_bug.cgi?id=77643

Reviewed by Pavel Feldman.

Source/WebCore:

Test: inspector/styles/updates-during-dom-traversal.html

* inspector/front-end/StylesSidebarPane.js:
(WebInspector.StylesSidebarPane.prototype._executeRebuildUpdate):

LayoutTests:

* inspector/styles/updates-during-dom-traversal-expected.txt: Added.
* inspector/styles/updates-during-dom-traversal.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@106560 268f45cc-cd09-0410-ab3c-d52691b4dbfc