Revert of Streamline frame detach

Source/core/page/Page.cpp

Index: Source/core/page/Page.cpp
diff --git a/Source/core/page/Page.cpp b/Source/core/page/Page.cpp
index 1ee917e6c518abe095f9c0fa5afc52a57e1e1cc4..ea017a3640d25f70b17faa25f4081577e7a59620 100644
--- a/Source/core/page/Page.cpp
+++ b/Source/core/page/Page.cpp
@@ -128,6 +128,7 @@
     , m_editorClient(pageClients.editorClient)
     , m_spellCheckerClient(pageClients.spellCheckerClient)
     , m_storageClient(pageClients.storageClient)
+    , m_subframeCount(0)
     , m_openedByDOM(false)
     , m_tabKeyCyclesThroughElements(true)
     , m_defersLoading(false)
@@ -439,6 +440,19 @@
 {
     return m_timerAlignmentInterval;
 }
+
+#if ENABLE(ASSERT)
+void Page::checkSubframeCountConsistency() const
+{
+    ASSERT(m_subframeCount >= 0);
+
+    int subframeCount = 0;
+    for (Frame* frame = mainFrame(); frame; frame = frame->tree().traverseNext())
+        ++subframeCount;
+
+    ASSERT(m_subframeCount + 1 == subframeCount);
+}
+#endif
 
 void Page::setVisibilityState(PageVisibilityState visibilityState, bool isInitialState)
 {