Fixes tests that use internals.observeGC to work with Ignition.

third_party/WebKit/LayoutTests/fast/dom/NodeIterator/NodeIterator-dont-overcollect.html

Index: third_party/WebKit/LayoutTests/fast/dom/NodeIterator/NodeIterator-dont-overcollect.html
diff --git a/third_party/WebKit/LayoutTests/fast/dom/NodeIterator/NodeIterator-dont-overcollect.html b/third_party/WebKit/LayoutTests/fast/dom/NodeIterator/NodeIterator-dont-overcollect.html
index 96fe55a72d4b4bb46c6bc779903bb03290ec671f..7b5d83fc727ccdb3a207ec910907da2711614c69 100644
--- a/third_party/WebKit/LayoutTests/fast/dom/NodeIterator/NodeIterator-dont-overcollect.html
+++ b/third_party/WebKit/LayoutTests/fast/dom/NodeIterator/NodeIterator-dont-overcollect.html
@@ -11,10 +11,14 @@
     };
     var nodeIterator = document.createNodeIterator(document, NodeFilter.SHOW_ELEMENT, callback, false);
 
-    var callbackObservation = internals.observeGC(callback);
+    // Do not pass the object as a parameter to observeGC function. This may
+    // remain live on this function's stack preventing GC from collecting
+    // it. Accessing the object inside an inner function will prevent any
+    // unneeded references on this function's stack.
+    var callbackObservation = internals.observeGC((() => {return callback;})());
     callback = null;
-    var nodeFilterObservation = internals.observeGC(nodeIterator.filter);
-    var nodeIteratorObservation = internals.observeGC(nodeIterator);
+    var nodeFilterObservation = internals.observeGC((() => {return nodeIterator.filter;})());
+    var nodeIteratorObservation = internals.observeGC((() => {return nodeIterator;})());
 
     gc();
     shouldBeFalse('nodeFilterObservation.wasCollected');