Devtools Animations: Update timeline controls and UI

Source/devtools/front_end/elements/AnimationControlPane.js

Index: Source/devtools/front_end/elements/AnimationControlPane.js
diff --git a/Source/devtools/front_end/elements/AnimationControlPane.js b/Source/devtools/front_end/elements/AnimationControlPane.js
index 7f1eddb73e0b6d966bbd63e29d07a3bafd9a5428..b0604bc6859625d30dd2d79010b444321226a1aa 100644
--- a/Source/devtools/front_end/elements/AnimationControlPane.js
+++ b/Source/devtools/front_end/elements/AnimationControlPane.js
@@ -135,9 +135,14 @@ WebInspector.AnimationControlPane.ButtonProvider.prototype = {
             this._animationControlPaneModeClick();
     },
 
-    _nodeChanged: function()
+    /**
+     * @param {!Event=} event
+     */
+    _nodeChanged: function(event)
     {
         this._button.setEnabled(!!WebInspector.context.flavor(WebInspector.DOMNode));
+        if (event && this._animationTimeline)

[pfeldman, 2015/06/05 14:34:34]

When is event undefined?

[samli, 2015/06/09 03:53:08]

Called in WebInspector.AnimationControlPane.ButtonProvider().

+            this._animationTimeline.setNode(/** @type {!WebInspector.DOMNode} */(event.data));
     },
 
     /**