Move regexp implementation into its own folder.

src/regexp/jsregexp.h

Index: src/regexp/jsregexp.h
diff --git a/src/jsregexp.h b/src/regexp/jsregexp.h
similarity index 99%
rename from src/jsregexp.h
rename to src/regexp/jsregexp.h
index ff7759bfec631bde43a0f59b2f61622bfdd79c62..39e702149d2294882adb4cf4c6a6e3d97c00dcc7 100644
--- a/src/jsregexp.h
+++ b/src/regexp/jsregexp.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_JSREGEXP_H_
-#define V8_JSREGEXP_H_
+#ifndef V8_REGEXP_JSREGEXP_H_
+#define V8_REGEXP_JSREGEXP_H_
 
 #include "src/allocation.h"
 #include "src/assembler.h"
@@ -1661,4 +1661,4 @@ class RegExpEngine: public AllStatic {
 
 } }  // namespace v8::internal
 
-#endif  // V8_JSREGEXP_H_
+#endif  // V8_REGEXP_JSREGEXP_H_