Only count legacy parser usage if legacy parser had effect.

test/cctest/test-date.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 149 matching lines @@
   }
   CheckDST((august_20 + september_10) / 2);
   CheckDST(september_10);
   CheckDST(september_10 + 2 * 3600);
   CheckDST(september_10 + 2 * 3600 - 1000);
   CheckDST(august_20 + 2 * 3600);
   CheckDST(august_20 + 2 * 3600 - 1000);
   CheckDST(august_20);
 }
 
+namespace {
+int legacy_parse_count = 0;
+void DateParseLegacyCounterCallback(v8::Isolate* isolate,
+                                    v8::Isolate::UseCounterFeature feature) {
+  if (feature == v8::Isolate::kLegacyDateParser) legacy_parse_count++;
+}
+}  // anonymous namespace
+
+TEST(DateParseLegacyUseCounter) {
+  CcTest::InitializeVM();
+  v8::HandleScope scope(CcTest::isolate());
+  LocalContext context;
+  CcTest::isolate()->SetUseCounterCallback(DateParseLegacyCounterCallback);
+  CHECK_EQ(0, legacy_parse_count);
+  CompileRun("Date.parse('2015-02-31')");
+  CHECK_EQ(0, legacy_parse_count);
+  CompileRun("Date.parse('2015-02-31T11:22:33.444Z01:23')");
+  CHECK_EQ(0, legacy_parse_count);
+  CompileRun("Date.parse('2015-02-31T11:22:33.444')");
+  CHECK_EQ(0, legacy_parse_count);
+  CompileRun("Date.parse('2000 01 01')");
+  CHECK_EQ(1, legacy_parse_count);
+  CompileRun("Date.parse('2015-02-31T11:22:33.444     ')");
+  CHECK_EQ(1, legacy_parse_count);
+}
+
 #ifdef V8_I18N_SUPPORT
 TEST(DateCacheVersion) {
   FLAG_allow_natives_syntax = true;
   v8::Isolate* isolate = CcTest::isolate();
   v8::Isolate::Scope isolate_scope(isolate);
   v8::HandleScope scope(isolate);
   v8::Local<v8::Context> context = v8::Context::New(isolate);
   v8::Context::Scope context_scope(context);
   v8::Local<v8::Number> date_cache_version =
       v8::Local<v8::Number>::Cast(CompileRun("%DateCacheVersion()"));
 
   CHECK(date_cache_version->IsNumber());
   CHECK_EQ(0.0, date_cache_version->NumberValue(context).FromMaybe(-1.0));
 
   v8::Date::DateTimeConfigurationChangeNotification(isolate);
 
   date_cache_version =
       v8::Local<v8::Number>::Cast(CompileRun("%DateCacheVersion()"));
   CHECK(date_cache_version->IsNumber());
   CHECK_EQ(1.0, date_cache_version->NumberValue(context).FromMaybe(-1.0));
 }
 #endif  // V8_I18N_SUPPORT