Address the remaining review comments on http://chromiumcodereview.appspot.com/9431029.

lib/compiler/implementation/typechecker.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.
 
 class TypeCheckerTask extends CompilerTask {
   TypeCheckerTask(Compiler compiler) : super(compiler);
   String get name() => "Type checker";
 
   static final bool LOG_FAILURES = false;
 
@@ skipping 43 matching lines @@
 
   /** Combine the information about two control-flow edges that are joined. */
   StatementType join(StatementType other) {
     return (this === other) ? this : MAYBE_RETURNING;
   }
 
   String toString() => stringName;
 }
 
 class InterfaceType implements Type {
-  final SourceString name;
   final Element element;
   final Link<Type> arguments;
 
-  const InterfaceType(this.name, this.element,
+  const InterfaceType(name, this.element,
                       [this.arguments = const EmptyLink<Type>()]);
 
+  SourceString get name() => element.name;
+
   toString() {
     StringBuffer sb = new StringBuffer();
     sb.add(name.slowToString());
     if (!arguments.isEmpty()) {
       sb.add('<');
-      arguments.printOn(sb);
+      arguments.printOn(sb, ', ');
       sb.add('>');
     }
     return sb.toString();
   }
 }
 
 class FunctionType implements Type {
   final Element element;
   final Type returnType;
   final Link<Type> parameterTypes;
@@ skipping 640 matching lines @@
   }
 
   visitCatchBlock(CatchBlock node) {
     fail(node);
   }
 
   visitTypedef(Typedef node) {
     fail(node);
   }
 }