Share locals between members

pkg/compiler/lib/src/ssa/locals_handler.dart

 // Copyright (c) 2016, 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.
 
 import '../closure.dart';
 import '../common.dart';
 import '../elements/elements.dart';
 import '../elements/entities.dart';
 import '../elements/types.dart';
 import '../io/source_information.dart';
@@ skipping 404 matching lines @@
   }
 
   /// Sets the [element] to [value]. If the element is boxed or stored in a
   /// closure then the method generates code to set the value.
   void updateLocal(Local local, HInstruction value,
       {SourceInformation sourceInformation}) {
     if (value is HRef) {
       HRef ref = value;
       value = ref.value;
     }
-    assert(!isStoredInClosureField(local));
+    assert(!isStoredInClosureField(local),
+        "Local $local is stored in a closure field.");
     if (isAccessedDirectly(local)) {
       directLocals[local] = value;
     } else if (isBoxed(local)) {
       FieldEntity redirect = redirectionMapping[local];
       assert(redirect != null);
       BoxLocal localBox;
       if (redirect is BoxFieldElement) {
         localBox = redirect.box;
       } else if (redirect is JBoxedField) {
         localBox = redirect.box;
@@ skipping 256 matching lines @@
   final MemberEntity memberContext;
 
   // Avoid slow Object.hashCode.
   final int hashCode = _nextHashCode = (_nextHashCode + 1).toUnsigned(30);
   static int _nextHashCode = 0;
 
   SyntheticLocal(this.name, this.executableContext, this.memberContext);
 
   toString() => 'SyntheticLocal($name)';
 }