[builtins] Apply ES2016 conditional default timezone semantics

test/mjsunit/date-parse.js

Index: test/mjsunit/date-parse.js
diff --git a/test/mjsunit/date-parse.js b/test/mjsunit/date-parse.js
index e623827df7b8235b9c87157a944e23624ebb629d..ff9c41d14948170d47b6b07b0bbd2b3d305522a7 100644
--- a/test/mjsunit/date-parse.js
+++ b/test/mjsunit/date-parse.js
@@ -232,6 +232,20 @@ var testCasesMisc = [
     ['Saturday, 01-Jan-00 08:00 PM UT', 946756800000],
     ['01 Jan 00 08:00 PM +0000', 946756800000]];
 
+// TODO(littledan): This is an hack that could break in historically
+// changing timezones that happened on this day, but allows us to
+// check the date value for local times.
+var localOffset = new Date('2000-01-01').getTimezoneOffset()*1000*60;
+
+// Sanity check which is even more of a hack: in the timezones where
+// these tests are likely to be run, the offset is nonzero because
+// dates which don't include Z are in the local timezone.
+if (this.Intl &&
+    ["America/Los_Angeles", "Europe/Berlin", "Europe/Madrid"].indexOf(
+        Intl.DateTimeFormat().resolvedOptions().timeZone) != -1) {
+  assertTrue(localOffset != 0);
+}
+
 // Test different version of the ES5 date time string format.
 var testCasesES5Misc = [
     ['2000-01-01T08:00:00.000Z', 946713600000],
@@ -245,9 +259,18 @@ var testCasesES5Misc = [
     ['2000-01T08:00:00.099Z', 946713600099],
     ['2000-01T08:00:00.999Z', 946713600999],
     ['2000-01T00:00:00.001-08:00', 946713600001],
-    ['2000-01-01T24:00', 946771200000],
-    ['2000-01-01T24:00:00', 946771200000],
-    ['2000-01-01T24:00:00.000', 946771200000],
+    // If the timezone is absent and time is present, use local time

[ulan, 2017/02/15 21:35:04]

The array is named "testCasesES5Misc" but this is testing ES2016 semantics.

Should we rename the array or move these test to separate array?

+    ['2000-01-02T00:00', 946771200000 + localOffset],
+    ['2000-01-02T00:00:00', 946771200000 + localOffset],
+    ['2000-01-02T00:00:00.000', 946771200000 + localOffset],
+    // If timezone is absent and time is absent, use UTC
+    ['2000-01-02', 946771200000],
+    ['2000-01-02', 946771200000],
+    ['2000-01-02', 946771200000],
+    // 24-hour wraparound case
+    ['2000-01-01T24:00Z', 946771200000],
+    ['2000-01-01T24:00:00Z', 946771200000],
+    ['2000-01-01T24:00:00.000Z', 946771200000],
     ['2000-01-01T24:00:00.000Z', 946771200000]];
 
 var testCasesES5MiscNegative = [