Test: Fix tst_qqmlecmascript::exportDate

Get timezone offset of the date specified and not the default value.

Change-Id: I58dba896098cbee72a2e4ec15ba2c928121e6cff
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>

tests/auto/qml/qqmlecmascript/data/exportDate.2.qml

@@ -12,7 +12,7 @@ MyTypeObject {
 
         // The test date is 2009-5-12 23:59:59 (local time)
         var compare = new Date(2009, 5-1, 12, 23, 59, 59)
-        var compareOffset = new Date().getTimezoneOffset()
+        var compareOffset = compare.getTimezoneOffset()
 
         // The date is already in local time, so we can use the partial values directly
         var dtAdjusted = dt

tests/auto/qml/qqmlecmascript/data/exportDate.qml

@@ -12,7 +12,7 @@ MyTypeObject {
 
         // The test date is 2009-5-12 00:00:01 (local time)
         var compare = new Date(2009, 5-1, 12, 0, 0, 1)
-        var compareOffset = new Date().getTimezoneOffset()
+        var compareOffset = compare.getTimezoneOffset()
 
         // The date is already in local time, so we can use the partial values directly
         var dtAdjusted = dt