Bug 1386222 - Ensure that we always respect the undo/redo transaction history when modifying the <xul:textbox>.value dynamically through script; r=bzbarsky

dom/html/HTMLInputElement.cpp

@@ -3001,6 +3001,14 @@ HTMLInputElement::SetValueInternal(const nsAString& aValue,
   NS_PRECONDITION(GetValueMode() != VALUE_MODE_FILENAME,
                   "Don't call SetValueInternal for file inputs");
 
+  // We want to remember if the SetValueInternal() call is being made for a XUL
+  // element.  We do that by looking at the parent node here, and if that node
+  // is a XUL node, we consider our control a XUL control.
+  nsIContent* parent = GetParent();
+  if (parent && parent->IsXULElement()) {
+    aFlags |= nsTextEditorState::eSetValue_ForXUL;
+  }
+
   switch (GetValueMode()) {
     case VALUE_MODE_VALUE:
     {