Revert of Experimental support for RegExp lookbehind.

src/regexp/bytecodes-irregexp.h

Index: src/regexp/bytecodes-irregexp.h
diff --git a/src/regexp/bytecodes-irregexp.h b/src/regexp/bytecodes-irregexp.h
index 2dbfbc0b82c1cff4babd901aac34533564273208..d6110a3cb53696fcf3e29cabc103af30a5e34002 100644
--- a/src/regexp/bytecodes-irregexp.h
+++ b/src/regexp/bytecodes-irregexp.h
@@ -57,17 +57,15 @@
 V(CHECK_GT,          36, 8)   /* bc8 pad8 uc16 addr32                       */ \
 V(CHECK_NOT_BACK_REF, 37, 8)  /* bc8 reg_idx24 addr32                       */ \
 V(CHECK_NOT_BACK_REF_NO_CASE, 38, 8) /* bc8 reg_idx24 addr32                */ \
-V(CHECK_NOT_BACK_REF_BACKWARD, 39, 8)         /* bc8 reg_idx24 addr32       */ \
-V(CHECK_NOT_BACK_REF_NO_CASE_BACKWARD, 40, 8) /* bc8 reg_idx24 addr32       */ \
-V(CHECK_NOT_REGS_EQUAL, 41, 12) /* bc8 regidx24 reg_idx32 addr32            */ \
-V(CHECK_REGISTER_LT, 42, 12)  /* bc8 reg_idx24 value32 addr32               */ \
-V(CHECK_REGISTER_GE, 43, 12)  /* bc8 reg_idx24 value32 addr32               */ \
-V(CHECK_REGISTER_EQ_POS, 44, 8) /* bc8 reg_idx24 addr32                     */ \
-V(CHECK_AT_START,    45, 8)   /* bc8 pad24 addr32                           */ \
-V(CHECK_NOT_AT_START, 46, 8)  /* bc8 offset24 addr32                        */ \
-V(CHECK_GREEDY,      47, 8)   /* bc8 pad24 addr32                           */ \
-V(ADVANCE_CP_AND_GOTO, 48, 8) /* bc8 offset24 addr32                        */ \
-V(SET_CURRENT_POSITION_FROM_END, 49, 4) /* bc8 idx24                        */
+V(CHECK_NOT_REGS_EQUAL, 39, 12) /* bc8 regidx24 reg_idx32 addr32            */ \
+V(CHECK_REGISTER_LT, 40, 12)  /* bc8 reg_idx24 value32 addr32               */ \
+V(CHECK_REGISTER_GE, 41, 12)  /* bc8 reg_idx24 value32 addr32               */ \
+V(CHECK_REGISTER_EQ_POS, 42, 8) /* bc8 reg_idx24 addr32                     */ \
+V(CHECK_AT_START,    43, 8)   /* bc8 pad24 addr32                           */ \
+V(CHECK_NOT_AT_START, 44, 8)  /* bc8 pad24 addr32                           */ \
+V(CHECK_GREEDY,      45, 8)   /* bc8 pad24 addr32                           */ \
+V(ADVANCE_CP_AND_GOTO, 46, 8) /* bc8 offset24 addr32                        */ \
+V(SET_CURRENT_POSITION_FROM_END, 47, 4) /* bc8 idx24                        */
 
 #define DECLARE_BYTECODES(name, code, length) \
   static const int BC_##name = code;