[runtime] Migrate several Date builtins to C++.

src/runtime/runtime-i18n.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.
 
 
 #ifdef V8_I18N_SUPPORT
 #include "src/runtime/runtime-utils.h"
 
 #include "src/api.h"
 #include "src/api-natives.h"
@@ skipping 371 matching lines @@
   v8::String::Utf8Value utf8_date(v8::Utils::ToLocal(date_string));
   icu::UnicodeString u_date(icu::UnicodeString::fromUTF8(*utf8_date));
   icu::SimpleDateFormat* date_format =
       DateFormat::UnpackDateFormat(isolate, date_format_holder);
   if (!date_format) return isolate->ThrowIllegalOperation();
 
   UErrorCode status = U_ZERO_ERROR;
   UDate date = date_format->parse(u_date, status);
   if (U_FAILURE(status)) return isolate->heap()->undefined_value();
 
-  Handle<Object> result;
+  Handle<JSDate> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-      isolate, result, Execution::NewDate(isolate, static_cast<double>(date)));
-  DCHECK(result->IsJSDate());
+      isolate, result,
+      JSDate::New(isolate->date_function(), isolate->date_function(),
+                  static_cast<double>(date)));
   return *result;
 }
 
 
 RUNTIME_FUNCTION(Runtime_CreateNumberFormat) {
   HandleScope scope(isolate);
 
   DCHECK(args.length() == 3);
 
   CONVERT_ARG_HANDLE_CHECKED(String, locale, 0);
@@ skipping 336 matching lines @@
   } else if (status >= UBRK_WORD_IDEO && status < UBRK_WORD_IDEO_LIMIT) {
     return *isolate->factory()->NewStringFromStaticChars("ideo");
   } else {
     return *isolate->factory()->NewStringFromStaticChars("unknown");
   }
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_I18N_SUPPORT