Provide default month for Date.UTC

After https://github.com/tc39/ecma262/pull/642, Date.UTC no longer requires
the month argument to be specified. The spec provides 0 as its default value.

This CL updates the builtins-date.cc code to reflect that and drops the test
suppression for test262/built-ins/Date/UTC/return-value.

BUG=v8:5534

Review-Url: https://codereview.chromium.org/2689173003
Cr-Commit-Position: refs/heads/master@{#43193}

src/builtins/builtins-date.cc

@@ -302,8 +302,8 @@ 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,

test/test262/test262.status

@@ -447,9 +447,6 @@
   # https://bugs.chromium.org/p/v8/issues/detail?id=5855
   'language/expressions/async-generators/*': [SKIP],
 
-  # https://bugs.chromium.org/p/v8/issues/detail?id=5534
-  'built-ins/Date/UTC/return-value': [FAIL],
-
   # https://bugs.chromium.org/p/v8/issues/detail?id=4614
   'built-ins/SharedArrayBuffer/*': [SKIP],
   'built-ins/Atomics/*': [SKIP],