Experimental support for RegExp lookbehind.

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index c609e578d4353f976932632ff301429d457dcbf6..d1681d35476b6516b198888abb81897db0c29112 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -2051,6 +2051,7 @@ 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,
@@ -2553,6 +2554,7 @@ bool Genesis::InstallExperimentalNatives() {
   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++) {