Oilpan: introduce sticky forcedForTesting flag to ensure that a precise

LayoutTests/svg/animations/smil-leak-dynamically-added-element-instances.svg

 <svg id="svg" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" onload="load()">
 <defs>
     <rect id="rect" width="100" height="100" />
 </defs>
 <g id="g"/>
 <text x="50" y="50" id="log"/>
+<script xlink:href="../../resources/js-test.js"></script>
 <script id="script">
 <![CDATA[
 
 var g = document.getElementById("g");
 
 function log(message) {
     var logDiv = document.getElementById('log');
     logDiv.appendChild(document.createTextNode(message));
 }
 
 function createAnimatedRectInstance() {
     var use = document.createElementNS("http://www.w3.org/2000/svg", "use");
     use.setAttributeNS("http://www.w3.org/1999/xlink", "href", "#rect");
     
     var anim = document.createElementNS("http://www.w3.org/2000/svg", "animate");
     anim.setAttribute("attributeType", "XML");
     anim.setAttribute("attributeName", "x");
     anim.setAttribute("from", "100");
     anim.setAttribute("to", "0");
     anim.setAttribute("begin", "0s");
     anim.setAttribute("dur", "10.0s");
     anim.setAttribute("repeatCount", 1);
 
     use.appendChild(anim);
 
     return use;
 }
 
 function cleanup() {
-    // Collect garbage before recording starting live node count, in case there are live elements from previous tests.
-    // FIXME: Unclear why two calls to collect() are required, see crbug.com/307614
-    GCController.collect();
-    GCController.collect();
-    var originalLiveElements = internals.numberOfLiveNodes();
+    collectGarbage(function() {
+        var originalLiveElements = internals.numberOfLiveNodes();
 
-    while (g.hasChildNodes())
-        g.removeChild(g.lastChild);
+        while (g.hasChildNodes())
+            g.removeChild(g.lastChild);
 
-    GCController.collect();
+        collectGarbage(function() {
+            // FIXME: Why 400 and not 200?
+            var liveDelta = originalLiveElements - internals.numberOfLiveNodes() - 400;
+            if (liveDelta == 0)
+                log("PASS");
+            else
+                log("FAIL: " + liveDelta + " extra live node(s)");
 
-    // FIXME: Why 400 and not 200?
-    var liveDelta = originalLiveElements - internals.numberOfLiveNodes() - 400;
-    if (liveDelta == 0)
-        log("PASS");
-    else
-        log("FAIL: " + liveDelta + " extra live node(s)");
-
-    testRunner.notifyDone();
+            testRunner.notifyDone();
+        });
+    });
 }
 
 function addMoreInstances() {
     for (var i = 0; i < 50; i++)
         g.appendChild(createAnimatedRectInstance());
     
     setTimeout(cleanup, 0);
 }
 
 function startTest() {
@@ skipping 10 matching lines @@
     } else {
         log("This test only works when run with the testRunner, GCController, and internals available.");
         return;
     }
 
     setTimeout(startTest, 0);
 }
 ]]>
 </script>
 </svg>