Move regexp implementation into its own folder.

src/regexp/mips/regexp-macro-assembler-mips.cc

Index: src/regexp/mips/regexp-macro-assembler-mips.cc
diff --git a/src/mips/regexp-macro-assembler-mips.cc b/src/regexp/mips/regexp-macro-assembler-mips.cc
similarity index 99%
rename from src/mips/regexp-macro-assembler-mips.cc
rename to src/regexp/mips/regexp-macro-assembler-mips.cc
index f29802130dfab880e0cf3910a8cc7f5be6893af7..8519a5337e594d2d0859671a4bb1893836ea5eec 100644
--- a/src/mips/regexp-macro-assembler-mips.cc
+++ b/src/regexp/mips/regexp-macro-assembler-mips.cc
@@ -6,15 +6,15 @@
 
 #if V8_TARGET_ARCH_MIPS
 
+#include "src/regexp/mips/regexp-macro-assembler-mips.h"
+
 #include "src/code-stubs.h"
 #include "src/log.h"
 #include "src/macro-assembler.h"
-#include "src/regexp-macro-assembler.h"
-#include "src/regexp-stack.h"
+#include "src/regexp/regexp-macro-assembler.h"
+#include "src/regexp/regexp-stack.h"
 #include "src/unicode.h"
 
-#include "src/mips/regexp-macro-assembler-mips.h"
-
 namespace v8 {
 namespace internal {