feat(filter): support conversion to timezone other than UTC

Closes #10858

Author: shahata

src/ng/filter/filters.js

@@ -485,10 +485,13 @@ function dateFilter($locale) {
     }
 
     var dateTimezoneOffset = date.getTimezoneOffset();
-    if (timezone && timezone === 'UTC') {
-      date = new Date(date.getTime());
-      date.setMinutes(date.getMinutes() + date.getTimezoneOffset());
-      dateTimezoneOffset = 0;
+    if (timezone) {
+      var requestedTimezoneOffset = Date.parse('Jan 01, 1970 00:00:00 ' + timezone) / 60000;
+      if (!isNaN(requestedTimezoneOffset)) {
+        date = new Date(date.getTime());
+        date.setMinutes(date.getMinutes() + dateTimezoneOffset - requestedTimezoneOffset);
+        dateTimezoneOffset = requestedTimezoneOffset;
+      }
     }
     forEach(parts, function(value) {
       fn = DATE_FORMATS[value];

test/ng/filter/filtersSpec.js

@@ -458,5 +458,14 @@ describe('filters', function() {
       expect(date(new Date(Date.UTC(2003, 8, 10, 3, 2, 4)), 'yyyy-MM-dd HH-mm-ss', 'UTC')).toEqual('2003-09-10 03-02-04');
       expect(date(new Date(Date.UTC(2003, 8, 10, 3, 2, 4)), 'yyyy-MM-dd HH-mm-ssZ', 'UTC')).toEqual('2003-09-10 03-02-04+0000');
     });
+
+    it('should support conversion to any timezone', function() {
+      expect(date(new Date(Date.UTC(2003, 8, 10, 3, 2, 4)), 'yyyy-MM-dd HH-mm-ssZ', 'GMT+0500')).toEqual('2003-09-10 08-02-04+0500');
+    });
+
+    it('should fallback to default timezone in case an unknown timezone was passed', function() {
+      var value = new angular.mock.TzDate(-2, '2003-09-10T01:02:04.000Z');
+      expect(date(value, 'yyyy-MM-dd HH-mm-ssZ', 'WTF')).toEqual('2003-09-10 03-02-04+0200');
+    });
   });
 });