Cleanup LayoutTests that define a function gc().

third_party/WebKit/LayoutTests/fast/dom/DOMImplementation/detached-doctype.html

 <p>Test for <a href="https://bugs.webkit.org/show_bug.cgi?id=26402">bug 26402<a/>: Crashes when using a detached DocumentType node.</p>
 <p>PASS if no crash.</p>
+<script src="../../../resources/gc.js"></script>
 <SCRIPT>
-function gc()
-{
-    if (window.GCController)
-        return GCController.collect();
-
-    for (var i = 0; i < 10000; i++)
-        var s = new String("");
-}
 
 if (window.testRunner)
     testRunner.dumpAsText();
 
 var o = document.implementation.createDocumentType('x', null, null);
 var doc = document.implementation.createDocument("doc", null);
 for (i in o) {
     try { o[i]; } catch (e) {}
     try { o[i](); } catch (e) {}
 }
 o.addEventListener("click", function() {}, true);
 o.removeEventListener("click", function() {}, true);
 o.childNodes;
 o.childNodes.item(0);
 o.firstChild;
 gc();
 document.write("DONE");
 </SCRIPT>