Support type argument substitution on unnamed mixin applications.

sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart

Index: sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart b/sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart
index 8cc5e3a8e118632e1ef74656f15ecaf26c6aa5be..66ce51afe450009ea12a5860e303fdfdf00b87db 100644
--- a/sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart
@@ -354,8 +354,14 @@ class ClassEmitter extends CodeEmitterHelper {
     buffer.write(jsAst.prettyPrint(builder.toObjectInitializer(), compiler));
     String reflectionName = task.getReflectionName(classElement, className);
     if (reflectionName != null) {
+      reflectionName = '+$reflectionName';
+    } else if (classElement.isUnnamedMixinApplication &&
+               backend.isNeededForReflection(classElement)) {
+      reflectionName = '-$className';
+    }
+    if (reflectionName != null) {
       if (!backend.isNeededForReflection(classElement)) {
-        buffer.write(',$n$n"+$reflectionName": 0');
+        buffer.write(',$n$n"$reflectionName": 0');
       } else {
         List<int> types = <int>[];
         if (classElement.supertype != null) {
@@ -365,7 +371,7 @@ class ClassEmitter extends CodeEmitterHelper {
         for (DartType interface in classElement.interfaces) {
           types.add(task.metadataEmitter.reifyType(interface));
         }
-        buffer.write(',$n$n"+$reflectionName": $types');
+        buffer.write(',$n$n"$reflectionName": $types');
       }
     }
   }