Web Inspector: Flame Chart. Minor changes for the popover.
https://bugs.webkit.org/show_bug.cgi?id=112331

Reviewed by Yury Semikhatsky.

popover timeout needs to be decreased a bit.
hidePopover call in onMouseMove doesn't necessary.
We have to keep anchor element unmodified if the hovered item didn't changed.

* inspector/front-end/FlameChart.js:
(WebInspector.FlameChart):
(WebInspector.FlameChart.prototype._onMouseMove):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@145796 268f45cc-cd09-0410-ab3c-d52691b4dbfc