dart2js: Make sure that super classes have their inheritance chain set up correctly.

pkg/compiler/lib/src/js_emitter/startup_emitter/fragment_emitter.dart

 // Copyright (c) 2015, 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 dart2js.js_emitter.startup_emitter.model_emitter;
 
 /// The name of the property that stores the tear-off getter on a static
 /// function.
 ///
 /// This property is only used when isolates are used.
@@ skipping 759 matching lines @@
   }
 
   /// Emits the inheritance block of the fragment.
   ///
   /// In this section prototype chains are updated and mixin functions are
   /// copied.
   js.Statement emitInheritance(Fragment fragment) {
     List<js.Expression> inheritCalls = <js.Expression>[];
     List<js.Expression> mixinCalls = <js.Expression>[];
 
+    Set<Class> emittedClasses = new Set<Class>();
+
+    void emitInheritanceForClass(cls) {
+      if (cls == null || emittedClasses.contains(cls)) return;
+
+      Class superclass = cls.superclass;
+      emitInheritanceForClass(superclass);
+
+      js.Expression superclassReference = (superclass == null)
+          ? new js.LiteralNull()
+          : classReference(superclass);
+
+      inheritCalls.add(js.js('inherit(#, #)',
+          [classReference(cls), superclassReference]));
+
+      emittedClasses.add(cls);
+    }
+
     for (Library library in fragment.libraries) {
       for (Class cls in library.classes) {
-        js.Expression superclassReference = (cls.superclass == null)
-            ? new js.LiteralNull()
-            : classReference(cls.superclass);
-
-        inheritCalls.add(js.js('inherit(#, #)',
-            [classReference(cls), superclassReference]));
+        emitInheritanceForClass(cls);
 
         if (cls.isMixinApplication) {
           MixinApplication mixin = cls;
           mixinCalls.add(js.js('mixin(#, #)',
               [classReference(cls), classReference(mixin.mixinClass)]));
         }
       }
     }
 
     return new js.Block([inheritCalls, mixinCalls]
@@ skipping 501 matching lines @@
     }
     statements.add(js.js.statement("setOrUpdateInterceptorsByTag(#);",
         js.objectLiteral(interceptorsByTag)));
     statements.add(js.js.statement("setOrUpdateLeafTags(#);",
         js.objectLiteral(leafTags)));
     statements.add(subclassAssignment);
 
     return new js.Block(statements);
   }
 }