Add back references. Since "back references" is two words...

src/assembler-re2k.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 
 // A light-weight assembler for the Regexp2000 byte code.
 
 #ifndef V8_ASSEMBLER_RE2K_H_
 #define V8_ASSEMBLER_RE2K_H_
 
 namespace v8 { namespace internal {
 
 
@@ skipping 53 matching lines @@
   void CheckNotCharacter(uc16 c, Label* on_mismatch);
 
   // Used to check current char register against a range.
   void CheckCharacterLT(uc16 limit, Label* on_less);
   void CheckCharacterGT(uc16 limit, Label* on_greater);
 
   // Checks current position for a match against a
   // previous capture.  Advances current position by the length of the capture
   // iff it matches.  The capture is stored in a given register and the
   // the register after.  If a register contains -1 then the other register
-  // mush always contain -1 and the on_mismatch label will never be called.
-  void CheckBackref(int capture_index, Label* on_mismatch);
+  // must always contain -1 and the on_mismatch label will never be called.
+  void CheckNotBackReference(int capture_index, Label* on_mismatch);
 
   // Checks a register for strictly-less-than or greater-than-or-equal.
   void CheckRegisterLT(int reg_index, uint16_t vs, Label* on_less_than);
   void CheckRegisterGE(int reg_index, uint16_t vs, Label* on_greater_equal);
 
   // Subtracts a 16 bit value from the current character, uses the result to
   // look up in a bit array, uses the result of that decide whether to fall
   // though (on 1) or jump to the on_zero label (on 0).
   void LookupMap1(uc16 start, Label* bit_map, Label* on_zero);
 
@@ skipping 40 matching lines @@
   // True if the assembler owns the buffer, false if buffer is external.
   bool own_buffer_;
 
   void Expand();
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ASSEMBLER_RE2K_H_