Modify some gc related layout tests to work with Ignition.

third_party/WebKit/LayoutTests/storage/indexeddb/cursor-leak.html

Index: third_party/WebKit/LayoutTests/storage/indexeddb/cursor-leak.html
diff --git a/third_party/WebKit/LayoutTests/storage/indexeddb/cursor-leak.html b/third_party/WebKit/LayoutTests/storage/indexeddb/cursor-leak.html
index 6fbda670510d9e452212b566256119c293bd8e87..a055dfc2356ae1264c4a8dcd3efde5a5403d718e 100644
--- a/third_party/WebKit/LayoutTests/storage/indexeddb/cursor-leak.html
+++ b/third_party/WebKit/LayoutTests/storage/indexeddb/cursor-leak.html
@@ -32,19 +32,21 @@ function onOpen(evt)
     };
     tx.oncomplete = function() {
         db.close();
-
-        // Try and induce a leak by a reference cycle from DOM to V8 and back.
-        // If the v8 value of cursor.key (etc) is only held by the cursor's
-        // V8 wrapper then there will be no leak.
-        cursor.key.cursor = cursor;
-        cursor.primaryKey.cursor = cursor;
-        cursor.value.cursor = cursor;
-
-        // Do not pass the object directly 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.
-        cursorObserver = internals.observeGC((() => {return cursor;})());
+        
+        // Do initialization work in an inner function to avoid references to
+        // objects remaining live on this function's stack frame
+        // (http://crbug.com/595672/).
+        function initialize() {
+            // Try and induce a leak by a reference cycle from DOM to V8 and
+            // back. If the v8 value of cursor.key (etc) is only held by the
+            // cursor's V8 wrapper then there will be no leak.
+            cursor.key.cursor = cursor;
+            cursor.primaryKey.cursor = cursor;
+            cursor.value.cursor = cursor;
+            cursorObserver = internals.observeGC(cursor);
+        }
+
+        initialize();
 
         cursorRequest = null;
         cursor = null;

[rmcilroy, 2016/05/20 14:53:39]

Ditto with cursorRequest and cursor

[mythria, 2016/05/23 10:35:45]

We can't do this with cursorRequest or cursor. The initialize function is
executed on transaction complete. However we need to open cursor earlier. The
initialize function and the initialization of variables happens at different
times, so I can't move them. I can't make them local variables either. So
leaving this as is.