Implement WebFrame::swap.

Source/web/OpenedFrameTracker.cpp

Index: Source/web/OpenedFrameTracker.cpp
diff --git a/Source/web/OpenedFrameTracker.cpp b/Source/web/OpenedFrameTracker.cpp
index d56397bddce1cc74d95676385da1185baf39f449..2120f339a6d4f91c0ebb075c83f58f4eae36aed4 100644
--- a/Source/web/OpenedFrameTracker.cpp
+++ b/Source/web/OpenedFrameTracker.cpp
@@ -15,9 +15,12 @@ OpenedFrameTracker::OpenedFrameTracker()
 
 OpenedFrameTracker::~OpenedFrameTracker()
 {
-    HashSet<WebFrame*>::iterator end = m_openedFrames.end();
-    for (HashSet<WebFrame*>::iterator it = m_openedFrames.begin(); it != end; ++it)
-        (*it)->m_opener = 0;
+    updateOpener(0);
+}
+
+bool OpenedFrameTracker::isEmpty() const
+{
+    return m_openedFrames.isEmpty();
 }
 
 void OpenedFrameTracker::add(WebFrame* frame)
@@ -30,4 +33,11 @@ void OpenedFrameTracker::remove(WebFrame* frame)
     m_openedFrames.remove(frame);
 }
 
+void OpenedFrameTracker::updateOpener(WebFrame* frame)
+{
+    HashSet<WebFrame*>::iterator end = m_openedFrames.end();
+    for (HashSet<WebFrame*>::iterator it = m_openedFrames.begin(); it != end; ++it)
+        (*it)->m_opener = frame;
+}
+
 } // namespace blink