Roll 50: Updated for push to origin/master.

tools/dom/scripts/systemhtml.py

Index: tools/dom/scripts/systemhtml.py
diff --git a/tools/dom/scripts/systemhtml.py b/tools/dom/scripts/systemhtml.py
index 11db1f7a9dcf454a43d0f6d34526fcb527de955a..d86216c92657dece808ede7f7dbfd101c873ba0c 100644
--- a/tools/dom/scripts/systemhtml.py
+++ b/tools/dom/scripts/systemhtml.py
@@ -502,7 +502,10 @@ class HtmlDartInterfaceGenerator(object):
     if IsCustomType(self._interface.id):
       pass
     elif 'Callback' in self._interface.ext_attrs:
-      self.GenerateCallback()
+      if len(GetCallbackHandlers(self._interface)) > 0:
+        self.GenerateCallback()
+      else:
+        return
     else:
       self.GenerateInterface()
 
@@ -902,6 +905,8 @@ class Dart2JSBackend(HtmlDartGenerator):
       indexed_getter = 'this.getItem(index)'
     elif any(op.id == 'item' for op in self._interface.operations):
       indexed_getter = 'this.item(index)'
+    else:
+      indexed_getter = False
 
     if indexed_getter:
       self._members_emitter.Emit(