Revert of Issue FrameDestructionObserver::frameDestroyed() notification on detach.

Source/core/frame/LocalFrame.cpp

Index: Source/core/frame/LocalFrame.cpp
diff --git a/Source/core/frame/LocalFrame.cpp b/Source/core/frame/LocalFrame.cpp
index ab088f9515fbb1b458b1ea8354492de93743d3d7..09e5bda9a8322fe3a6d9ed1d5e5a51fc90aecc50 100644
--- a/Source/core/frame/LocalFrame.cpp
+++ b/Source/core/frame/LocalFrame.cpp
@@ -204,10 +204,19 @@
     // Verify that the FrameView has been cleared as part of detaching
     // the frame owner.
     ASSERT(!m_view);
+
 #if !ENABLE(OILPAN)
     // Oilpan: see setDOMWindow() comment why it is acceptable not to
-    // explicitly call setDOMWindow() here.
+    // mirror the non-Oilpan call below.
+    //
+    // Also, FrameDestructionObservers that live longer than this
+    // frame object keep weak references to the frame; those will be
+    // automatically cleared by the garbage collector. Hence, explicit
+    // frameDestroyed() notifications aren't needed.
     setDOMWindow(nullptr);
+
+    for (const auto& frameDestructionObserver : m_destructionObservers)
+        frameDestructionObserver->frameDestroyed();
 #endif
 }
 
@@ -272,7 +281,6 @@
     m_loader.stopAllLoaders();
     if (!client())
         return;
-
     m_loader.detach();
     // Notify ScriptController that the frame is closing, since its cleanup ends up calling
     // back to FrameLoaderClient via WindowProxy.
@@ -286,14 +294,6 @@
     // finalization. Too late to access various heap objects at that
     // stage.
     m_loader.clear();
-
-    // Signal frame destruction here rather than in the destructor.
-    // Main motivation is to avoid being dependent on its exact timing (Oilpan.)
-    for (const auto& frameDestructionObserver : m_destructionObservers)
-        frameDestructionObserver->frameDestroyed();
-
-    m_destructionObservers.clear();
-    m_supplements.clear();
 }
 
 SecurityContext* LocalFrame::securityContext() const