[regexp] move regexp parser into own files.

src/parsing/scanner.h

Index: src/parsing/scanner.h
diff --git a/src/parsing/scanner.h b/src/parsing/scanner.h
index abaccf57254cb38bdf963556b63502a52430d2dc..1d0aba0611a82de422253544720998d6e1923d11 100644
--- a/src/parsing/scanner.h
+++ b/src/parsing/scanner.h
@@ -28,17 +28,6 @@ class ParserRecorder;
 class UnicodeCache;
 
 
-// Returns the value (0 .. 15) of a hexadecimal character c.
-// If c is not a legal hexadecimal character, returns a value < 0.
-inline int HexValue(uc32 c) {
-  c -= '0';
-  if (static_cast<unsigned>(c) <= 9) return c;
-  c = (c | 0x20) - ('a' - '0');  // detect 0x11..0x16 and 0x31..0x36.
-  if (static_cast<unsigned>(c) <= 5) return c + 10;
-  return -1;
-}
-
-
 // ---------------------------------------------------------------------
 // Buffered stream of UTF-16 code units, using an internal UTF-16 buffer.
 // A code unit is a 16 bit value representing either a 16 bit code point