interceptedNames should include all interceptor method generated, not just the ones called.

dart/sdk/lib/_internal/compiler/implementation/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;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked;
 
   JavaScriptItemCompilationContext()
@@ skipping 80 matching lines @@
   final Namer namer;
 
   /**
    * Interface used to determine if an object has the JavaScript
    * indexing behavior. The interface is only visible to specific
    * libraries.
    */
   ClassElement jsIndexingBehaviorInterface;
 
   /**
-   * A collection of selectors of intercepted method calls. The
-   * emitter uses this set to generate the [:ObjectInterceptor:] class
-   * whose members just forward the call to the intercepted receiver.
-   */
-  final Set<Selector> usedInterceptors;
-
-  /**
    * A collection of selectors that must have a one shot interceptor
    * generated.
    */
   final Map<String, Selector> oneShotInterceptors;
 
   /**
    * The members of instantiated interceptor classes: maps a member name to the
    * list of members that have that name. This map is used by the codegen to
    * know whether a send must be intercepted or not.
    */
@@ skipping 40 matching lines @@
   /// Holds the method "disableTreeShaking" in js_mirrors when
   /// dart:mirrors has been loaded.
   FunctionElement disableTreeShakingMarker;
 
   /// Holds the method "preserveNames" in js_mirrors when
   /// dart:mirrors has been loaded.
   FunctionElement preserveNamesMarker;
 
   JavaScriptBackend(Compiler compiler, bool generateSourceMap, bool disableEval)
       : namer = determineNamer(compiler),
-        usedInterceptors = new Set<Selector>(),
         oneShotInterceptors = new Map<String, Selector>(),
         interceptedElements = new Map<SourceString, Set<Element>>(),
         rti = new RuntimeTypes(compiler),
         specializedGetInterceptors = new Map<String, Set<ClassElement>>(),
         super(compiler, JAVA_SCRIPT_CONSTANT_SYSTEM) {
     emitter = disableEval
         ? new CodeEmitterNoEvalTask(compiler, namer, generateSourceMap)
         : new CodeEmitterTask(compiler, namer, generateSourceMap);
     builder = new SsaBuilderTask(this);
     optimizer = new SsaOptimizerTask(this);
     generator = new SsaCodeGeneratorTask(this);
   }
 
   static Namer determineNamer(Compiler compiler) {
     return compiler.enableMinification ?
         new MinifyNamer(compiler) :
         new Namer(compiler);
   }
 
   bool isInterceptorClass(ClassElement element) {
     if (element == null) return false;
     if (element.isNative()) return true;
     if (interceptedClasses.contains(element)) return true;
     if (classesMixedIntoNativeClasses.contains(element)) return true;
     return false;
   }
 
-  void addInterceptedSelector(Selector selector) {
-    usedInterceptors.add(selector);
-  }
-
   String registerOneShotInterceptor(Selector selector) {
     Set<ClassElement> classes = getInterceptedClassesOn(selector.name);
     String name = namer.getOneShotInterceptorName(selector, classes);
     if (!oneShotInterceptors.containsKey(name)) {
       registerSpecializedGetInterceptor(classes);
       oneShotInterceptors[name] = selector;
     }
     return name;
   }
 
@@ skipping 921 matching lines @@
  }
 
   void registerStaticUse(Element element, Enqueuer enqueuer) {
     if (element == disableTreeShakingMarker) {
       enqueuer.enqueueEverything();
       compiler.disableTypeInferenceForMirrors = true;
     } else if (element == preserveNamesMarker) {
     }
   }
 }