Use the instruction iterator rather than an explicit loop in more places.

runtime/vm/intermediate_language.h

 // 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.
 
 #ifndef VM_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 1688 matching lines @@
 class FlowGraphBuilder;
 class Environment;
 
 #define FORWARD_DECLARATION(type) class type##Instr;
 FOR_EACH_INSTRUCTION(FORWARD_DECLARATION)
 #undef FORWARD_DECLARATION
 
 
 // Functions required in all concrete instruction classes.
 #define DECLARE_INSTRUCTION(type)                                              \
-  virtual Instruction* Accept(FlowGraphVisitor* visitor);                      \
+  virtual void Accept(FlowGraphVisitor* visitor);                              \
   virtual bool Is##type() const { return true; }                               \
   virtual type##Instr* As##type() { return this; }                             \
   virtual intptr_t InputCount() const;                                         \
   virtual Value* InputAt(intptr_t i) const;                                    \
   virtual void SetInputAt(intptr_t i, Value* value);                           \
   virtual const char* DebugName() const { return #type; }                      \
   virtual void PrintTo(BufferFormatter* f) const;                              \
   virtual void PrintToVisualizer(BufferFormatter* f) const;
 
 
@@ skipping 21 matching lines @@
     return IsBlockEntry() ? reinterpret_cast<BlockEntryInstr*>(this) : NULL;
   }
   virtual bool IsDefinition() const { return false; }
   virtual Definition* AsDefinition() { return NULL; }
 
   virtual intptr_t InputCount() const = 0;
   virtual Value* InputAt(intptr_t i) const = 0;
   virtual void SetInputAt(intptr_t i, Value* value) = 0;
 
   // Visiting support.
-  virtual Instruction* Accept(FlowGraphVisitor* visitor) = 0;
+  virtual void Accept(FlowGraphVisitor* visitor) = 0;
 
   Instruction* previous() const { return previous_; }
   void set_previous(Instruction* instr) {
     ASSERT(!IsBlockEntry());
     previous_ = instr;
   }
 
   Instruction* next() const { return next_; }
   void set_next(Instruction* instr) {
     ASSERT(!IsGraphEntry());
@@ skipping 673 matching lines @@
   const GrowableArray<BlockEntryInstr*>& block_order_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_