Merge 159961 "Defer the real work in updateCompositingLayers unt..."

LayoutTests/fast/events/touch/resources/compositor-touch-hit-rects.js

 function listener() {
 }
 
 function log(msg) {
     var span = document.createElement("span");
     document.getElementById("console").appendChild(span);
     span.innerHTML = msg + '<br />';
 }
 
 function nameForNode(node) {
@@ skipping 112 matching lines @@
     // want to visualize the results.
     visualize = true;
 }
 
 if (window.internals) {
     window.internals.settings.setMockScrollbarsEnabled(true);
     window.internals.settings.setForceCompositingMode(true);
 }
 
 window.onload = function() {
+    if (window.internals)
+        window.internals.forceCompositingUpdate(document);
+
     // Run each general test case.
     var tests = document.querySelectorAll('.testcase');
     for ( var i = 0; i < tests.length; i++)
         testElement(tests[i]);
 
     if (window.additionalTests)
         additionalTests();
 
     if (!visualize && window.internals) {
         var testContainer = document.getElementById("tests");
         testContainer.parentNode.removeChild(testContainer);
     }
 
     document.documentElement.setAttribute('done', 'true');
 };