Optimize static field and context load/stores as part of CSE pass.

runtime/vm/intermediate_language.h

 // 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.
 
 #ifndef VM_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 2301 matching lines @@
  public:
   CurrentContextInstr() { }
 
   DECLARE_INSTRUCTION(CurrentContext)
   virtual CompileType ComputeType() const;
 
   virtual bool CanDeoptimize() const { return false; }
 
   virtual bool HasSideEffect() const { return false; }
 
+  virtual bool AttributesEqual(Instruction* other) const { return true; }
+
  private:
   DISALLOW_COPY_AND_ASSIGN(CurrentContextInstr);
 };
 
 
 class ClosureCallInstr : public TemplateDefinition<0> {
  public:
   ClosureCallInstr(ClosureCallNode* node,
                    ZoneGrowableArray<PushArgumentInstr*>* arguments)
       : ast_node_(*node),
@@ skipping 2608 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_