Improve NSM handling.

runtime/lib/invocation_mirror_patch.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.
 
 // NOTE: When making changes to this class, please also update
-// `VmTarget.instantiateInvocation` in `pkg/kernel/lib/target/vm.dart`.
+// `VmTarget.instantiateInvocation` and `VmTarget._invocationType` in
+// `pkg/kernel/lib/target/vm.dart`.
 class _InvocationMirror implements Invocation {
   // Constants describing the invocation type.
   // _FIELD cannot be generated by regular invocation mirrors.
   static const int _METHOD = 0;
   static const int _GETTER = 1;
   static const int _SETTER = 2;
   static const int _FIELD = 3;
   static const int _LOCAL_VAR = 4;
   static const int _TYPE_SHIFT = 0;
   static const int _TYPE_BITS = 3;
@@ skipping 113 matching lines @@
 
   _InvocationMirror(this._functionName, this._argumentsDescriptor,
       this._arguments, this._isSuperInvocation);
 
   static _allocateInvocationMirror(String functionName,
       List argumentsDescriptor, List arguments, bool isSuperInvocation) {
     return new _InvocationMirror(
         functionName, argumentsDescriptor, arguments, isSuperInvocation);
   }
 }