[regexp] do not include irregexp interpreter by default.

src/regexp/regexp-macro-assembler-irregexp.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_REGEXP_REGEXP_MACRO_ASSEMBLER_IRREGEXP_H_
 #define V8_REGEXP_REGEXP_MACRO_ASSEMBLER_IRREGEXP_H_
 
+#ifdef V8_INTERPRETED_REGEXP
+
 #include "src/regexp/regexp-macro-assembler.h"
 
 namespace v8 {
 namespace internal {
 
-#ifdef V8_INTERPRETED_REGEXP
-
 // A light-weight assembler for the Irregexp byte code.
 class RegExpMacroAssemblerIrregexp: public RegExpMacroAssembler {
  public:
   // Create an assembler. Instructions and relocation information are emitted
   // into a buffer, with the instructions starting from the beginning and the
   // relocation information starting from the end of the buffer. See CodeDesc
   // for a detailed comment on the layout (globals.h).
   //
   // If the provided buffer is NULL, the assembler allocates and grows its own
   // buffer, and buffer_size determines the initial buffer size. The buffer is
@@ skipping 99 matching lines @@
   int advance_current_offset_;
   int advance_current_end_;
 
   Isolate* isolate_;
 
   static const int kInvalidPC = -1;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(RegExpMacroAssemblerIrregexp);
 };
 
-#endif  // V8_INTERPRETED_REGEXP
-
 }  // namespace internal
 }  // namespace v8
 
+#endif  // V8_INTERPRETED_REGEXP
+
 #endif  // V8_REGEXP_REGEXP_MACRO_ASSEMBLER_IRREGEXP_H_