Revert of Experimental support for RegExp lookbehind.

src/bootstrapper.cc

 // Copyright 2014 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.
 
 #include "src/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/code-stubs.h"
 #include "src/extensions/externalize-string-extension.h"
@@ skipping 2033 matching lines @@
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_sloppy_let)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_rest_parameters)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_default_parameters)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_destructuring)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_object_observe)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_regexps)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_unicode_regexps)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_completion)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_tolength)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_do_expressions)
-EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_regexp_lookbehind)
 
 
 static void SimpleInstallFunction(Handle<JSObject>& base, const char* name,
                                   Builtins::Name call, int len, bool adapt) {
   Handle<JSFunction> fun =
       InstallFunction(base, name, JS_OBJECT_TYPE, JSObject::kHeaderSize,
                       MaybeHandle<JSObject>(), call);
   if (adapt) {
     fun->shared()->set_internal_formal_parameter_count(len);
   } else {
@@ skipping 482 matching lines @@
       "native harmony-object-observe.js", nullptr};
   static const char* harmony_sharedarraybuffer_natives[] = {
       "native harmony-sharedarraybuffer.js", "native harmony-atomics.js", NULL};
   static const char* harmony_concat_spreadable_natives[] = {nullptr};
   static const char* harmony_simd_natives[] = {"native harmony-simd.js",
                                                nullptr};
   static const char* harmony_tolength_natives[] = {nullptr};
   static const char* harmony_completion_natives[] = {nullptr};
   static const char* harmony_do_expressions_natives[] = {nullptr};
   static const char* harmony_regexp_subclass_natives[] = {nullptr};
-  static const char* harmony_regexp_lookbehind_natives[] = {nullptr};
 
   for (int i = ExperimentalNatives::GetDebuggerCount();
        i < ExperimentalNatives::GetBuiltinsCount(); i++) {
 #define INSTALL_EXPERIMENTAL_NATIVES(id, desc)                                \
   if (FLAG_##id) {                                                            \
     for (size_t j = 0; id##_natives[j] != NULL; j++) {                        \
       Vector<const char> script_name = ExperimentalNatives::GetScriptName(i); \
       if (strncmp(script_name.start(), id##_natives[j],                       \
                   script_name.length()) == 0) {                               \
         if (!Bootstrapper::CompileExperimentalBuiltin(isolate(), i)) {        \
@@ skipping 668 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8