Move regexp implementation into its own folder.

src/regexp/x64/regexp-macro-assembler-x64.h

Index: src/regexp/x64/regexp-macro-assembler-x64.h
diff --git a/src/x64/regexp-macro-assembler-x64.h b/src/regexp/x64/regexp-macro-assembler-x64.h
similarity index 98%
rename from src/x64/regexp-macro-assembler-x64.h
rename to src/regexp/x64/regexp-macro-assembler-x64.h
index b2492f101166cd614894acf0ffd526f93a00b972..d690dc19749301ae8c789047da3b2c51120da5eb 100644
--- a/src/x64/regexp-macro-assembler-x64.h
+++ b/src/regexp/x64/regexp-macro-assembler-x64.h
@@ -2,12 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef V8_X64_REGEXP_MACRO_ASSEMBLER_X64_H_
-#define V8_X64_REGEXP_MACRO_ASSEMBLER_X64_H_
+#ifndef V8_REGEXP_X64_REGEXP_MACRO_ASSEMBLER_X64_H_
+#define V8_REGEXP_X64_REGEXP_MACRO_ASSEMBLER_X64_H_
 
 #include "src/macro-assembler.h"
+#include "src/regexp/regexp-macro-assembler.h"
 #include "src/x64/assembler-x64.h"
-#include "src/x64/macro-assembler-x64.h"
 
 namespace v8 {
 namespace internal {
@@ -278,4 +278,4 @@ class RegExpMacroAssemblerX64: public NativeRegExpMacroAssembler {
 
 }}  // namespace v8::internal
 
-#endif  // V8_X64_REGEXP_MACRO_ASSEMBLER_X64_H_
+#endif  // V8_REGEXP_X64_REGEXP_MACRO_ASSEMBLER_X64_H_