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

third_party/WebKit/LayoutTests/fast/dom/MutationObserver/weak-callback-gc-crash.html

Index: third_party/WebKit/LayoutTests/fast/dom/MutationObserver/weak-callback-gc-crash.html
diff --git a/third_party/WebKit/LayoutTests/fast/dom/MutationObserver/weak-callback-gc-crash.html b/third_party/WebKit/LayoutTests/fast/dom/MutationObserver/weak-callback-gc-crash.html
index 4cb6819f14bb9594483aaa5efd7575a9f78e152a..1ee5ef6d432f3bed7c5364a1bf7676426c55cdd8 100644
--- a/third_party/WebKit/LayoutTests/fast/dom/MutationObserver/weak-callback-gc-crash.html
+++ b/third_party/WebKit/LayoutTests/fast/dom/MutationObserver/weak-callback-gc-crash.html
@@ -6,10 +6,15 @@ if (window.testRunner) {
     testRunner.waitUntilDone();
     testRunner.dumpAsText();
 }
-var observer = new MutationObserver(function() {console.log('Should not appear')});
-var div = document.createElement('div');
-observer.observe(div, {attributes: true});
-div.id = 'foo';
+var observer, div;
+function initializeObserver() {
+  observer = new MutationObserver(function() {console.log('Should not appear')});
+  div = document.createElement('div');
+  observer.observe(div, {attributes: true});
+  div.id = 'foo';
+}
+
+initializeObserver();
 div = null;
 observer = null;
 gc();