Removed UTC based calculation for diff()

All the diff unit tests now run in local time.

test/ringo/utils/dates_test.js

@@ -324,26 +324,17 @@ exports.testDiff = function() {
     });
 
     // 366 + 31 days = 397 days
-    a = new Date(Date.UTC(2012, 0, 1));
-    b = new Date(Date.UTC(2013, 1, 1));
-
-    assert.equal(dates.diff(a, b, "year"), 1);
-    assert.equal(dates.diff(a, b, "quarter"), 4);
-    assert.equal(dates.diff(a, b, "month"), 13);
-    assert.equal(dates.diff(a, b, "week"), 56);
-    assert.equal(dates.diff(a, b, "day"), 397);
-
-    // again Einstein, now with time diff
-    b = new Date(Date.UTC(2013, 1, 1, 20, 20, 20, 20));
+    a = new Date(2012, 0, 1);
+    b = new Date(2013, 1, 1);
     assert.equal(dates.diff(a, b, "year"), 1);
     assert.equal(dates.diff(a, b, "quarter"), 4);
     assert.equal(dates.diff(a, b, "month"), 13);
     assert.equal(dates.diff(a, b, "week"), 56);
     assert.equal(dates.diff(a, b, "day"), 397);
 
     // no difference in quarters
-    a = new Date(2013, 11, 1); // Q4/2013
-    b = new Date(2013, 9, 1);  // Q4/2013
+    a = new Date(2013, 11, 1, 12, 0, 0); // Q4/2013
+    b = new Date(2013, 9, 1, 12, 0, 0);  // Q4/2013
     assert.equal(dates.diff(a, b, "year"), 0);
     assert.equal(dates.diff(b, a, "year"), 0);
     assert.equal(dates.diff(a, b, "quarter"), 0);