Defer addStubs to class instantiation time.

pkg/compiler/lib/src/js_backend/backend.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of js_backend;
 
 const VERBOSE_OPTIMIZER_HINTS = false;
 
 const bool USE_CPS_IR = const bool.fromEnvironment("USE_CPS_IR");
 
@@ skipping 684 matching lines @@
       registerSpecializedGetInterceptor(classes);
       oneShotInterceptors[name] = selector;
     }
     return name;
   }
 
   /**
    * Record that [method] is called from a subclass via `super`.
    */
   bool maybeRegisterAliasedSuperMember(Element member, Selector selector) {
-    if (selector.isGetter || compiler.hasIncrementalSupport) {
+    if (!canUseAliasedSuperMember(member, selector)) {
       // Invoking a super getter isn't supported, this would require changes to
       // compact field descriptors in the emitter.
       // We also turn off this optimization in incremental compilation, to
       // avoid having to regenerate a method just because someone started
       // calling it through super.
       return false;
     }
     aliasedSuperMembers.add(member);
     return true;
   }
 
+  bool canUseAliasedSuperMember(Element member, Selector selector) {
+    return !selector.isGetter && !compiler.hasIncrementalSupport;
+  }
+
   /**
    * Returns `true` if [member] is called from a subclass via `super`.
    */
   bool isAliasedSuperMember(FunctionElement member) {
     return aliasedSuperMembers.contains(member);
   }
 
   bool isInterceptedMethod(Element element) {
     if (!element.isInstanceMember) return false;
     if (element.isGenerativeConstructorBody) {
@@ skipping 2116 matching lines @@
   }
 }
 
 /// Records that [constant] is used by the element behind [registry].
 class Dependency {
   final ConstantValue constant;
   final Element annotatedElement;
 
   const Dependency(this.constant, this.annotatedElement);
 }