DevTools: Bring back split view animation on show/hide sidebar button click.

R=dgozman@chromium.org, dgozman, pfeldman

Review URL: https://codereview.chromium.org/187833006

git-svn-id: svn://svn.chromium.org/blink/trunk@168623 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/devtools/front_end/SplitView.js

@@ -817,9 +817,9 @@ WebInspector.SplitView.prototype = {
         {
             var show = this._isShowingOne;
             if (show)
-                this.showBoth();
+                this.showBoth(true);
             else
-                this.hideSidebar();
+                this.hideSidebar(true);
         }
 
         return this._showHideSidebarButton;