Remove obsolete instruction HOuterContext.

src/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4675 matching lines @@
 
   return kUseCell;
 }
 
 
 HValue* HOptimizedGraphBuilder::BuildContextChainWalk(Variable* var) {
   ASSERT(var->IsContextSlot());
   HValue* context = environment()->context();
   int length = current_info()->scope()->ContextChainLength(var->scope());
   while (length-- > 0) {
-    context = Add<HOuterContext>(context);
+    context = AddLoadNamedField(
+        context, HObjectAccess::ForContextSlot(Context::PREVIOUS_INDEX));
   }
   return context;
 }
 
 
 void HOptimizedGraphBuilder::VisitVariableProxy(VariableProxy* expr) {
   if (expr->is_this()) {
     current_info()->set_this_has_uses(true);
   }
 
@@ skipping 6376 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal