Changing the alt or value attribute of an image input should change the text

shown when the image is broken.   Bug 408782, r+sr=dbaron, a=schrep

content/html/content/src/nsHTMLInputElement.cpp

@@ -2096,6 +2096,12 @@ nsHTMLInputElement::GetAttributeChangeHint(const nsIAtom* aAttribute,
     nsGenericHTMLFormElement::GetAttributeChangeHint(aAttribute, aModType);
   if (aAttribute == nsGkAtoms::type) {
     NS_UpdateHint(retval, NS_STYLE_HINT_FRAMECHANGE);
+  } else if (mType == NS_FORM_INPUT_IMAGE &&
+             (aAttribute == nsGkAtoms::alt ||
+              aAttribute == nsGkAtoms::value)) {
+    // We might need to rebuild our alt text.  Just go ahead and
+    // reconstruct our frame.  This should be quite rare..
+    NS_UpdateHint(retval, NS_STYLE_HINT_FRAMECHANGE);
   } else if (aAttribute == nsGkAtoms::value) {
     NS_UpdateHint(retval, NS_STYLE_HINT_REFLOW);
   } else if (aAttribute == nsGkAtoms::size &&