Provide default month for Date.UTC

src/builtins/builtins-date.cc

 // Copyright 2016 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/builtins/builtins-utils.h"
 #include "src/builtins/builtins.h"
 #include "src/code-factory.h"
 #include "src/code-stub-assembler.h"
 #include "src/dateparser-inl.h"
 
@@ skipping 284 matching lines @@
       isolate, string,
       Object::ToString(isolate, args.atOrUndefined(isolate, 1)));
   return *isolate->factory()->NewNumber(ParseDateTimeString(string));
 }
 
 // ES6 section 20.3.3.4 Date.UTC (year,month,date,hours,minutes,seconds,ms)
 BUILTIN(DateUTC) {
   HandleScope scope(isolate);
   int const argc = args.length() - 1;
   double year = std::numeric_limits<double>::quiet_NaN();
-  double month = std::numeric_limits<double>::quiet_NaN();
-  double date = 1.0, hours = 0.0, minutes = 0.0, seconds = 0.0, ms = 0.0;
+  double month = 0.0, date = 1.0, hours = 0.0, minutes = 0.0, seconds = 0.0,
+         ms = 0.0;
   if (argc >= 1) {
     Handle<Object> year_object;
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, year_object,
                                        Object::ToNumber(args.at(1)));
     year = year_object->Number();
     if (argc >= 2) {
       Handle<Object> month_object;
       ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, month_object,
                                          Object::ToNumber(args.at(2)));
       month = month_object->Number();
@@ skipping 847 matching lines @@
         Runtime::kThrowIncompatibleMethodReceiver, context,
         assembler.HeapConstant(assembler.factory()->NewStringFromAsciiChecked(
             "Date.prototype [ @@toPrimitive ]", TENURED)),
         receiver);
     assembler.Return(result);
   }
 }
 
 }  // namespace internal
 }  // namespace v8