Implement implicit constructors in mixin applications.

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;
 
 typedef void Recompile(Element element);
 
 class ReturnInfo {
   HType returnType;
@@ skipping 987 matching lines @@
       // differences.
       assert(interceptorMember.getEnclosingClass() != compiler.objectClass);
     });
   }
 
   void addInterceptorsForNativeClassMembers(
       ClassElement cls, Enqueuer enqueuer) {
     if (enqueuer.isResolutionQueue) {
       cls.ensureResolved(compiler);
       cls.forEachMember((ClassElement classElement, Element member) {
-          // All methods on [Object] are shadowed by [Interceptor].
-          if (classElement == compiler.objectClass) return;
-          Set<Element> set = interceptedElements.putIfAbsent(
-              member.name, () => new Set<Element>());
-          set.add(member);
-          if (classElement == jsInterceptorClass) return;
-          if (!classElement.isNative()) {
-            MixinApplicationElement mixinApplication = classElement;
-            assert(member.getEnclosingClass() == mixinApplication.mixin);
-            classesMixedIntoNativeClasses.add(mixinApplication.mixin);
-          }
-        },
-        includeSuperMembers: true);
+        if (member.isSynthesized) return;
+        // All methods on [Object] are shadowed by [Interceptor].
+        if (classElement == compiler.objectClass) return;
+        Set<Element> set = interceptedElements.putIfAbsent(
+            member.name, () => new Set<Element>());
+        set.add(member);
+        if (classElement == jsInterceptorClass) return;
+        if (!classElement.isNative()) {
+          MixinApplicationElement mixinApplication = classElement;
+          assert(member.getEnclosingClass() == mixinApplication.mixin);
+          classesMixedIntoNativeClasses.add(mixinApplication.mixin);
+        }
+      },
+      includeSuperMembers: true);
     }
   }
 
   void addInterceptors(ClassElement cls,
                        Enqueuer enqueuer,
                        TreeElements elements) {
     if (enqueuer.isResolutionQueue) {
       cls.ensureResolved(compiler);
       cls.forEachMember((ClassElement classElement, Element member) {
           // All methods on [Object] are shadowed by [Interceptor].
@@ skipping 811 matching lines @@
   ClassElement get constListImplementation => jsArrayClass;
   ClassElement get fixedListImplementation => jsFixedArrayClass;
   ClassElement get growableListImplementation => jsExtendableArrayClass;
   ClassElement get mapImplementation => mapLiteralClass;
   ClassElement get constMapImplementation => constMapLiteralClass;
   ClassElement get functionImplementation => jsFunctionClass;
   ClassElement get typeImplementation => typeLiteralClass;
   ClassElement get boolImplementation => jsBoolClass;
   ClassElement get nullImplementation => jsNullClass;
 }