[es6] implement default parameters via desugaring

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index f0779b4fe91e116f3855bd409e4445cca7d71d3d..3357a5042b96ec23abd69597cc82bb0bf512607d 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1767,6 +1767,7 @@ EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_destructuring)
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_object)
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_spread_arrays)
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_sharedarraybuffer)
+EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_default_parameters)
 
 
 void Genesis::InstallNativeFunctions_harmony_proxies() {
@@ -1798,6 +1799,7 @@ 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_spread_arrays)
+EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_default_parameters)
 
 void Genesis::InitializeGlobal_harmony_regexps() {
   Handle<JSObject> builtins(native_context()->builtins());
@@ -2442,6 +2444,7 @@ bool Genesis::InstallExperimentalNatives() {
   static const char* harmony_spread_arrays_natives[] = {nullptr};
   static const char* harmony_sharedarraybuffer_natives[] = {
       "native harmony-sharedarraybuffer.js", NULL};
+  static const char* harmony_default_parameters_natives[] = {nullptr};
 
   for (int i = ExperimentalNatives::GetDebuggerCount();
        i < ExperimentalNatives::GetBuiltinsCount(); i++) {