Suppress creation of Entity class (it's not being used. We can un-suppress later

lib/html/idl/dart/dart.idl

 
 // This file introduces / supplements and forces Dart declarations.
 
 module default {
   ClientRectList implements sequence<ClientRect>;
   CSSRuleList implements sequence<CSSRule>;
   CSSValueList implements sequence<CSSValue>;
   DOMMimeTypeArray implements sequence<DOMMimeType>;
   DOMPluginArray implements sequence<DOMPlugin>;
   EntryArray implements sequence<Entry>;
@@ skipping 372 matching lines @@
   };
 }
 
 module core {
   [Supplemental, Callback]
   interface RequestAnimationFrameCallback {
     // Webkit implements this as returning bool, but standard is void.
     [Suppressed] boolean handleEvent(in DOMTimeStamp time);
     [Custom] void handleEvent(in DOMTimeStamp time);
   };
+
+  [Suppressed]
+  interface Entity {};
 }