DevTools: avoid layout thrashing on Layers panel

third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js

Index: third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js b/third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js
index c8f4645b1693cbbd22c23c00b5400f4d6d283ef2..2cdf83aaa1e72e68149b7ebe0c0f4a483d3fdd15 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js
+++ b/third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js
@@ -286,6 +286,28 @@ TreeOutline.prototype = {
             event.consume(true);
     },
 
+    /**
+     * @param {!TreeElement} treeElement
+     */
+    _deferredScrollIntoView: function(treeElement)
+    {
+        if (!this._treeElementToScrollIntoView)
+            this.element.window().requestAnimationFrame(deferredScrollIntoView.bind(this));
+        this._treeElementToScrollIntoView = treeElement;
+        /**
+         * @this {TreeOutline}
+         */
+        function deferredScrollIntoView()
+        {
+            var treeElement = this._treeElementToScrollIntoView;
+            delete this._treeElementToScrollIntoView;
+            if (treeElement.treeOutline !== this || !treeElement.listItemElement)

[pfeldman, 2015/11/20 22:48:52]

nuke those

+                return;
+            treeElement.listItemElement.scrollIntoViewIfNeeded();
+            treeElement.onreveal();
+        }
+    },
+
     __proto__: WebInspector.Object.prototype
 }
 
@@ -861,9 +883,12 @@ TreeElement.prototype = {
             currentAncestor = currentAncestor.parent;
         }
 
-        this.listItemElement.scrollIntoViewIfNeeded();
+        this.treeOutline._deferredScrollIntoView(this);
+    },
 
-        this.onreveal();

[pfeldman, 2015/11/20 22:48:52]

I think you want it there synchronously.

+    _deferredScrollIntoView: function()

[pfeldman, 2015/11/20 22:48:52]

unused

+    {
+        this.listItemElement.scrollIntoViewIfNeeded();
     },
 
     /**