RegExp: Add support for the ES6-proposed sticky flag

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index dbf6e0e9c11d1288ca81e48af32ab9270dba3d20..8680e44eff05d607fe7132bf6864fa37fae5ae25 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1355,10 +1355,10 @@ void Genesis::InstallTypedArray(
 void Genesis::InitializeExperimentalGlobal() {
   // TODO(mstarzinger): Move this into Genesis::InitializeGlobal once we no
   // longer need to live behind flags, so functions get added to the snapshot.
+  Handle<JSObject> builtins(native_context()->builtins());
 
   if (FLAG_harmony_generators) {
     // Create generator meta-objects and install them on the builtins object.
-    Handle<JSObject> builtins(native_context()->builtins());
     Handle<JSObject> generator_object_prototype =
         factory()->NewJSObject(isolate()->object_function(), TENURED);
     Handle<JSFunction> generator_function_prototype = InstallFunction(
@@ -1417,6 +1417,12 @@ void Genesis::InitializeExperimentalGlobal() {
     native_context()->set_generator_object_prototype_map(
         *generator_object_prototype_map);
   }
+  Handle<HeapObject> flag(
+      FLAG_harmony_regexps ? heap()->true_value() : heap()->false_value());
+  PropertyAttributes attributes =
+      static_cast<PropertyAttributes>(DONT_DELETE | READ_ONLY);
+  Runtime::DefineObjectProperty(builtins, factory()->harmony_regexps_string(),
+                                flag, attributes).Assert();
 }