Have Frame::script() return a reference

Source/core/frame/Navigator.cpp

Index: Source/core/frame/Navigator.cpp
diff --git a/Source/core/frame/Navigator.cpp b/Source/core/frame/Navigator.cpp
index 7d93cde263ebee9164ce1440b5387a53b6510742..f0278fe9285ca80691359eed1b5174eef16b71c9 100644
--- a/Source/core/frame/Navigator.cpp
+++ b/Source/core/frame/Navigator.cpp
@@ -65,7 +65,7 @@ Navigator::~Navigator()
 // sites such as nwa.com -- the library thinks Safari is Netscape 4 if we don't do this!
 static bool shouldHideFourDot(Frame* frame)
 {
-    const String* sourceURL = frame->script()->sourceURL();
+    const String* sourceURL = frame->script().sourceURL();
     if (!sourceURL)
         return false;
     if (!(sourceURL->endsWith("/dqm_script.js") || sourceURL->endsWith("/dqm_loader.js") || sourceURL->endsWith("/tdqm_loader.js")))