[es6] implement default parameters via desugaring

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/base/utils/random-number-generator.h"
 #include "src/code-stubs.h"
@@ skipping 1676 matching lines @@
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_tostring)
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_sloppy)
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_unicode)
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_unicode_regexps)
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_computed_property_names)
 EMPTY_NATIVE_FUNCTIONS_FOR_FEATURE(harmony_rest_parameters)
 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_optional_params)
 
 
 void Genesis::InstallNativeFunctions_harmony_proxies() {
   if (FLAG_harmony_proxies) {
     INSTALL_NATIVE(JSFunction, "$proxyDerivedHasTrap", derived_has_trap);
     INSTALL_NATIVE(JSFunction, "$proxyDerivedGetTrap", derived_get_trap);
     INSTALL_NATIVE(JSFunction, "$proxyDerivedSetTrap", derived_set_trap);
     INSTALL_NATIVE(JSFunction, "$proxyEnumerate", proxy_enumerate);
   }
 }
@@ skipping 10 matching lines @@
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_object_literals)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_arrow_functions)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_proxies)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_sloppy)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_unicode)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_computed_property_names)
 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_optional_params)
 
 void Genesis::InitializeGlobal_harmony_regexps() {
   Handle<JSObject> builtins(native_context()->builtins());
 
   Handle<HeapObject> flag(FLAG_harmony_regexps ? heap()->true_value()
                                                : heap()->false_value());
   Runtime::SetObjectProperty(isolate(), builtins,
                              factory()->harmony_regexps_string(), flag,
                              STRICT).Assert();
 }
@@ skipping 588 matching lines @@
   static const char* harmony_unicode_regexps_natives[] = {nullptr};
   static const char* harmony_computed_property_names_natives[] = {nullptr};
   static const char* harmony_rest_parameters_natives[] = {nullptr};
   static const char* harmony_reflect_natives[] = {"native harmony-reflect.js",
                                                   nullptr};
   static const char* harmony_spreadcalls_natives[] = {
       "native harmony-spread.js", nullptr};
   static const char* harmony_destructuring_natives[] = {nullptr};
   static const char* harmony_object_natives[] = {"native harmony-object.js",
                                                  NULL};
+  static const char* harmony_optional_params_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 (!CompileExperimentalBuiltin(isolate(), i)) return false;          \
@@ skipping 622 matching lines @@
   return from + sizeof(NestingCounterType);
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 } }  // namespace v8::internal