Allow performance tests to test full rendering performance

PerformanceTests/Layout/Shapes/resources/shapes.js

 (function() {
     var templateParagraph = null;
     var templateFloatingNode = null;
     var DEFAULT_SHAPE_OBJECT_COUNT = 100;
 
     function createParagraphNode() {
         if (!templateParagraph) {
             templateParagraph = document.createElement("p");
             templateParagraph.innerHTML = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam at turpis placerat sapien congue viverra nec sed felis.\
                 Aenean aliquam, justo eu condimentum pharetra, arcu eros blandit metus, nec lacinia nisi orci vitae nunc.\
@@ skipping 49 matching lines @@
 
     function createShapeOutsideTest(properties, shapeObjectCount) {
         shapeObjectCount = shapeObjectCount || DEFAULT_SHAPE_OBJECT_COUNT;
 
         var floatingObjects = createFloatingObjects(properties, shapeObjectCount);
         document.body.appendChild(floatingObjects);
         return {
             description: "Testing shapes with " + properties['webkitShapeOutside'] +" using " + shapeObjectCount + " shapes.",
             run: function() {
                 applyFloating();
-                document.body.offsetTop;
+                PerfTestRunner.forceLayoutOrFullFrame();
             },
             setup: function() {
                 PerfTestRunner.resetRandomSeed();
-                document.body.offsetTop;
+                PerfTestRunner.forceLayoutOrFullFrame();
             },
             done: function() {
                 document.body.removeChild(floatingObjects);
                 templateParagraph = null;
             }
         };
     }
 
     window.createShapeOutsideTest = createShapeOutsideTest;
 
 })();