Change simpleName of anonymous mixin applications.

dart/sdk/lib/_internal/lib/js_mirrors.dart

Index: dart/sdk/lib/_internal/lib/js_mirrors.dart
diff --git a/dart/sdk/lib/_internal/lib/js_mirrors.dart b/dart/sdk/lib/_internal/lib/js_mirrors.dart
index d5db7e5f505c54dafa04c3d37eddaf99847fd051..1b738d18820e70558ea9f9a021ed6186d7bab1ea 100644
--- a/dart/sdk/lib/_internal/lib/js_mirrors.dart
+++ b/dart/sdk/lib/_internal/lib/js_mirrors.dart
@@ -491,6 +491,7 @@ class JsMixinApplication extends JsTypeMirror with JsObjectMirror
     implements ClassMirror {
   final ClassMirror superclass;
   final ClassMirror mixin;
+  Symbol _cachedSimpleName;
 
   JsMixinApplication(ClassMirror superclass, ClassMirror mixin,
                      String mangledName)
@@ -501,7 +502,11 @@ class JsMixinApplication extends JsTypeMirror with JsObjectMirror
   String get _prettyName => 'ClassMirror';
 
   Symbol get simpleName {
-    return s('${n(mixin.qualifiedName)}(${n(superclass.qualifiedName)})');
+    if (_cachedSimpleName != null) return _cachedSimpleName;
+    String superName = n(superclass.qualifiedName);
+    return _cachedSimpleName = (superName.contains(' with '))
+        ? s('$superName, ${n(mixin.qualifiedName)}')
+        : s('$superName with ${n(mixin.qualifiedName)}');
   }
 
   Symbol get qualifiedName => simpleName;