Remember the Timeline Overview zoom and selection between sessions.

https://bugs.webkit.org/show_bug.cgi?id=127369

Reviewed by Joseph Pecoraro.

* UserInterface/TimelineOverview.js:
(WebInspector.TimelineOverview):
(WebInspector.TimelineOverview.prototype.set secondsPerPixel):
(WebInspector.TimelineOverview.prototype._timeRangeSelectionChanged):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162528 268f45cc-cd09-0410-ab3c-d52691b4dbfc