Prevent reentrancy of WebFrameClient::didClearWindowObject.

Source/core/loader/FrameLoader.cpp

Index: Source/core/loader/FrameLoader.cpp
diff --git a/Source/core/loader/FrameLoader.cpp b/Source/core/loader/FrameLoader.cpp
index 48d220f6f91568247d524e6583d944382bd5d6cc..79c58bde28e8949779411b586a1046d77410f001 100644
--- a/Source/core/loader/FrameLoader.cpp
+++ b/Source/core/loader/FrameLoader.cpp
@@ -1365,6 +1365,10 @@ void FrameLoader::dispatchDidClearDocumentOfWindowObject()
 
     InspectorInstrumentation::didClearDocumentOfWindowObject(m_frame);
 
+    if (m_dispatchingDidClearWindowObjectInMainWorld)
+        return;
+    TemporaryChange<bool>
+        inDidClearWindowObject(m_dispatchingDidClearWindowObjectInMainWorld, true);
     // We just cleared the document, not the entire window object, but for the
     // embedder that's close enough.
     client()->dispatchDidClearWindowObjectInMainWorld();