Disable frame navigations during DocumentLoader detach in FrameLoader::startLoad

third_party/WebKit/Source/core/loader/FrameLoader.cpp

Index: third_party/WebKit/Source/core/loader/FrameLoader.cpp
diff --git a/third_party/WebKit/Source/core/loader/FrameLoader.cpp b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
index b93eecb9ad75eef3c0318c98911c816ac76abbc9..440f0a8f70bf33bfead5ab871e8c979e8386c600 100644
--- a/third_party/WebKit/Source/core/loader/FrameLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
@@ -1419,7 +1419,10 @@ void FrameLoader::startLoad(FrameLoadRequest& frameLoadRequest, FrameLoadType ty
         return;
 
     m_frame->document()->cancelParsing();
-    detachDocumentLoader(m_provisionalDocumentLoader);
+    if (m_provisionalDocumentLoader) {
+        FrameNavigationDisabler navigationDisabler(*m_frame);
+        detachDocumentLoader(m_provisionalDocumentLoader);
+    }
 
     // beforeunload fired above, and detaching a DocumentLoader can fire
     // events, which can detach this frame.