Reapply change to GVN all HFieldGet instructions.

lib/compiler/implementation/ssa/value_set.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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 ValueSet {
   int size = 0;
   List<HInstruction> table;
   ValueSetNode collisions;
   ValueSet() : table = new List<HInstruction>(8);
 
   bool isEmpty() => size == 0;
@@ skipping 28 matching lines @@
     for (ValueSetNode node = collisions; node !== null; node = node.next) {
       if (node.hashCode == hashCode) {
         HInstruction cached = node.value;
         if (cached.gvnEquals(instruction)) return cached;
       }
     }
     return null;
   }
 
   void kill(int flags) {
+    if (flags == 0) return;
     int depends = HInstruction.computeDependsOnFlags(flags);
     // Kill in the hash table.
     for (int index = 0, length = table.length; index < length; index++) {
       HInstruction instruction = table[index];
       if (instruction !== null && (instruction.flags & depends) != 0) {
         table[index] = null;
         size--;
       }
     }
     // Kill in the collisions list.
@@ skipping 84 matching lines @@
     assert(table.length == capacity);
   }
 }
 
 class ValueSetNode {
   final HInstruction value;
   final int hashCode;
   ValueSetNode next;
   ValueSetNode(this.value, this.hashCode, this.next);
 }