Bug 559766 - add accessibility support for @list on HTML input and for HTML datalist, r=marcoz

accessible/src/html/nsHTMLFormControlAccessible.cpp

@@ -511,6 +511,10 @@ nsHTMLTextFieldAccessible::NativeState()
     return state;
   }
 
+  // Expose autocomplete state if it has associated autocomplete list.
+  if (mContent->HasAttr(kNameSpaceID_None, nsGkAtoms::list))
+    return state | states::SUPPORTS_AUTOCOMPLETION;
+
   // No parent can mean a fake widget created for XUL textbox. If accessible
   // is unattached from tree then we don't care.
   if (mParent && gIsFormFillEnabled) {