[RootLayerScrolls] Fix frame scrolling layer in ScrollingCoordinator

third_party/WebKit/LayoutTests/scrollingcoordinator/resources/non-fast-scrollable-region-testing.js

 // setMockScrollbarsEnabled doesn't actually invalidate scrollbars
 // so if we don't set it immediately, they won't repaint/relayout
 // correctly!  http://crbug.com/365509
 if (window.internals)
     window.internals.settings.setMockScrollbarsEnabled(true);
 
 // Draws green overlays for non-fast scrollable regions. This provides a visual
 // feedback that is useful when running the test interactively.
 function drawNonFastScrollableRegionOverlays() {
     var overlay = document.createElement("div");
@@ skipping 16 matching lines @@
         overlay.appendChild(patch);
     }
 
     document.body.appendChild(overlay);
 }
 
 function rectToString(rect) {
     return '[' + [rect.left, rect.top, rect.width, rect.height].join(', ') + ']';
 }
 
+function sortRects(rects) {
+  Array.prototype.sort.call(rects, (a, b) => {

[skobes, 2017/01/28 02:00:04]

I thought of an easier way :)

Array.prototype.sort.call(rects, (a, b) => (
    a.height - b.height ||
    a.width - b.width ||
    a.top - b.top ||
    a.left - b.left));

+    return [
+      a.height - b.height, a.width - b.width, a.top - b.top, a.left - b.left
+    ].reduce((acc, val) => val || acc, 0);
+  });
+  return rects;
+}