Revert of Ensure RenderFrameHost & NavigationHandle are not destroyed during commit

content/browser/frame_host/render_frame_host_impl.h

Index: content/browser/frame_host/render_frame_host_impl.h
diff --git a/content/browser/frame_host/render_frame_host_impl.h b/content/browser/frame_host/render_frame_host_impl.h
index 1b9f27687db42068aaa4d8027f8a78575125bdf9..acef076ae2f1c4b7bc2b61fd40f5fc29ce772670 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -969,11 +969,6 @@ class CONTENT_EXPORT RenderFrameHostImpl : public RenderFrameHost,
   // called (no pending instance should be set).
   bool should_reuse_web_ui_;
 
-  // True if the RenderFrameHost is in the process of committing a navigation.
-  // This is temporary to help pinpoint the cause of crbug.com/589365.
-  // TODO(clamy): Remove once enough data has been gathered.
-  bool is_in_commit_;
-
   // PlzNavigate: The LoFi state of the last navigation. This is used during
   // history navigation of subframes to ensure that subframes navigate with the
   // same LoFi status as the top-level frame.