Have Frame::navigationScheduler() return a reference

Source/core/frame/DOMWindow.cpp

Index: Source/core/frame/DOMWindow.cpp
diff --git a/Source/core/frame/DOMWindow.cpp b/Source/core/frame/DOMWindow.cpp
index c496bc7ed511111e2b4b2a62e9337e033c8a8d9e..3c18ab8eeee1eb18fe997647a41ee5e6367ab9c5 100644
--- a/Source/core/frame/DOMWindow.cpp
+++ b/Source/core/frame/DOMWindow.cpp
@@ -1568,7 +1568,7 @@ void DOMWindow::setLocation(const String& urlString, DOMWindow* activeWindow, DO
         return;
 
     // We want a new history item if we are processing a user gesture.
-    m_frame->navigationScheduler()->scheduleLocationChange(activeDocument->securityOrigin(),
+    m_frame->navigationScheduler().scheduleLocationChange(activeDocument->securityOrigin(),
         // FIXME: What if activeDocument()->frame() is 0?
         completedURL, activeDocument->frame()->loader()->outgoingReferrer(),
         locking != LockHistoryBasedOnGestureState);
@@ -1712,7 +1712,7 @@ PassRefPtr<DOMWindow> DOMWindow::open(const String& urlString, const AtomicStrin
 
         // For whatever reason, Firefox uses the first window rather than the active window to
         // determine the outgoing referrer. We replicate that behavior here.
-        targetFrame->navigationScheduler()->scheduleLocationChange(
+        targetFrame->navigationScheduler().scheduleLocationChange(
             activeDocument->securityOrigin(),
             completedURL,
             firstFrame->loader()->outgoingReferrer(),