Fix for bug 403501 (Rich text editing broken after back, forward in history). r/sr=jst.

docshell/base/nsDocShell.cpp

@@ -1006,7 +1006,7 @@ nsDocShell::FirePageHideNotification(PRBool aIsUnload)
 
     // Now make sure our editor, if any, is torn down before we go
     // any farther.
-    if (mEditorData) {
+    if (mEditorData && aIsUnload) {
         mEditorData->TearDownEditor();
     }
 

editor/composer/src/nsEditingSession.cpp

@@ -763,7 +763,8 @@ nsEditingSession::OnStateChange(nsIWebProgress *aWebProgress,
     }
 
     // Document level notification...
-    if (aStateFlags & nsIWebProgressListener::STATE_IS_DOCUMENT) {
+    if (aStateFlags & nsIWebProgressListener::STATE_IS_DOCUMENT &&
+        !(aStateFlags & nsIWebProgressListener::STATE_RESTORING)) {
 #ifdef NOISY_DOC_LOADING
       printf("STATE_START & STATE_IS_DOCUMENT flags=%x\n", aStateFlags);
 #endif