Move regexp implementation into its own folder.

src/regexp/regexp-macro-assembler.h

Index: src/regexp/regexp-macro-assembler.h
diff --git a/src/regexp-macro-assembler.h b/src/regexp/regexp-macro-assembler.h
similarity index 98%
rename from src/regexp-macro-assembler.h
rename to src/regexp/regexp-macro-assembler.h
index df244249b630320117a6b7d6cc47dc3315a82e74..c3d94a6acfc288d79786eacf8cd6353a84cb9c58 100644
--- a/src/regexp-macro-assembler.h
+++ b/src/regexp/regexp-macro-assembler.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef V8_REGEXP_MACRO_ASSEMBLER_H_
-#define V8_REGEXP_MACRO_ASSEMBLER_H_
+#ifndef V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
+#define V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
 
 #include "src/ast.h"
 
@@ -247,4 +247,4 @@ class NativeRegExpMacroAssembler: public RegExpMacroAssembler {
 
 } }  // namespace v8::internal
 
-#endif  // V8_REGEXP_MACRO_ASSEMBLER_H_
+#endif  // V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_