[Timeline] Reduce flicker

Reposition scroll bar in Timeline with RAF instead of timeout;
this ensures that scroll bar is positioned after the current
digest (updating the width) but before the results are rendered
(avoiding flicker.) Fixes #997

platform/features/timeline/bundle.js

@@ -472,7 +472,7 @@ define([
                     "implementation": TimelineZoomController,
                     "depends": [
                         "$scope",
-                        "$timeout",
+                        "$window",
                         "TIMELINE_ZOOM_CONFIGURATION"
                     ]
                 },