[es6] implement default parameters via desugaring

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index d93c465b47dd20b7e290bf8865b747d4dcb88469..6d22ff1d569a0be31847ccd8e84558bf3f49e0b8 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1735,6 +1735,7 @@ EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_reflect)
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_spreadcalls)
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_destructuring)
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_object)
+EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_default_parameters)
 
 
 void Genesis::InstallNativeFunctions_harmony_proxies() {
@@ -1765,6 +1766,7 @@ EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_rest_parameters)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_spreadcalls)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_destructuring)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_object)
+EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_default_parameters)
 
 void Genesis::InitializeGlobal_harmony_regexps() {
   Handle<JSObject> builtins(native_context()->builtins());
@@ -2399,6 +2401,7 @@ bool Genesis::InstallExperimentalNatives() {
   static const char* harmony_destructuring_natives[] = {nullptr};
   static const char* harmony_object_natives[] = {"native harmony-object.js",
                                                  NULL};
+  static const char* harmony_default_parameters_natives[] = {nullptr};
 
   for (int i = ExperimentalNatives::GetDebuggerCount();
        i < ExperimentalNatives::GetBuiltinsCount(); i++) {