Reduce the number of #includes of compiler.h.

src/bit-vector.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_DATAFLOW_H_
 #define V8_DATAFLOW_H_
 
-#include "src/v8.h"
-
 #include "src/allocation.h"
-#include "src/ast.h"
-#include "src/compiler.h"
+#include "src/zone.h"
 
 namespace v8 {
 namespace internal {
 
 class BitVector : public ZoneObject {
  public:
   // Iterator for the elements of this BitVector.
   class Iterator BASE_EMBEDDED {
    public:
     explicit Iterator(BitVector* target)
@@ skipping 222 matching lines @@
     bits_ = new_bits;
   }
 
   BitVector* bits_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_DATAFLOW_H_