Simplify and fix implicit closure check, speed up Closure_equals

runtime/observatory/lib/src/elements/function_view.dart

 // Copyright (c) 2013, 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.
 
 library function_view_element;
 
 import 'dart:async';
 import 'dart:html';
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/src/elements/class_ref.dart';
@@ skipping 381 matching lines @@
     }
     _r.dirty();
   }
 
   static String _functionKindToString(M.FunctionKind kind) {
     switch (kind) {
       case M.FunctionKind.regular:
         return 'regular';
       case M.FunctionKind.closure:
         return 'closure';
+      case M.FunctionKind.implicitClosure:
+        return 'implicit closure';
       case M.FunctionKind.getter:
         return 'getter';
       case M.FunctionKind.setter:
         return 'setter';
       case M.FunctionKind.constructor:
         return 'constructor';
       case M.FunctionKind.implicitGetter:
         return 'implicit getter';
       case M.FunctionKind.implicitSetter:
         return 'implicit setter';
@@ skipping 16 matching lines @@
       case M.FunctionKind.stub:
         return 'stub';
       case M.FunctionKind.tag:
         return 'tag';
       case M.FunctionKind.signatureFunction:
         return 'signature function';
     }
     throw new Exception('Unknown Functionkind ($kind)');
   }
 }