Revert of Experimental support for RegExp lookbehind.

src/regexp/regexp-macro-assembler.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
 #define V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
 
 #include "src/ast.h"
 
 namespace v8 {
@@ skipping 53 matching lines @@
   // map.  The destinations vector has up to 4 labels.
   virtual void CheckCharacter(unsigned c, Label* on_equal) = 0;
   // Bitwise and the current character with the given constant and then
   // check for a match with c.
   virtual void CheckCharacterAfterAnd(unsigned c,
                                       unsigned and_with,
                                       Label* on_equal) = 0;
   virtual void CheckCharacterGT(uc16 limit, Label* on_greater) = 0;
   virtual void CheckCharacterLT(uc16 limit, Label* on_less) = 0;
   virtual void CheckGreedyLoop(Label* on_tos_equals_current_position) = 0;
-  virtual void CheckNotAtStart(int cp_offset, Label* on_not_at_start) = 0;
-  virtual void CheckNotBackReference(int start_reg, bool read_backward,
-                                     Label* on_no_match) = 0;
+  virtual void CheckNotAtStart(Label* on_not_at_start) = 0;
+  virtual void CheckNotBackReference(int start_reg, Label* on_no_match) = 0;
   virtual void CheckNotBackReferenceIgnoreCase(int start_reg,
-                                               bool read_backward,
                                                Label* on_no_match) = 0;
   // Check the current character for a match with a literal character.  If we
   // fail to match then goto the on_failure label.  End of input always
   // matches.  If the label is NULL then we should pop a backtrack address off
   // the stack and go to that.
   virtual void CheckNotCharacter(unsigned c, Label* on_not_equal) = 0;
   virtual void CheckNotCharacterAfterAnd(unsigned c,
                                          unsigned and_with,
                                          Label* on_not_equal) = 0;
   // Subtract a constant from the current character, then and with the given
@@ skipping 155 matching lines @@
                         int output_size,
                         Isolate* isolate);
 };
 
 #endif  // V8_INTERPRETED_REGEXP
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_