DOM - implement selection events (fire selectstart and selectionchange events on the input node when the selection in that editor changes)

dom/html/nsTextEditorState.cpp

@@ -92,6 +92,9 @@ public:
       return NS_OK;
     }
 
+    AutoHideSelectionChanges hideSelectionChanges
+      (mFrame->GetConstFrameSelection());
+
     if (mFrame) {
       // SetSelectionRange leads to Selection::AddRange which flushes Layout -
       // need to block script to avoid nested PrepareEditor calls (bug 642800).
@@ -1208,6 +1211,8 @@ nsTextEditorState::PrepareEditor(const nsAString *aValue)
     return NS_OK;
   }
 
+  AutoHideSelectionChanges hideSelectionChanges(GetConstFrameSelection());
+
   // Don't attempt to initialize recursively!
   InitializationGuard guard(*this);
   if (guard.IsInitializingRecursively()) {