fix(datepicker): don't use the locale in the default formatting function

By default the datepicker would insert the date into the view after passing it through toLocaleDateString.
This means that if the user's locale date string couldn't be parsed by `new Date`, the datepicker would have inserted an invalid date.
This change switches to always using the US date format, because it is parse-able by the Date constructor. This shouldn't be unexpected, because the documentation states that users should override the date functions if they're dealing with different kinds of date formats.

Fixes angular#7456.

src/components/datepicker/dateLocale.spec.js

@@ -47,6 +47,12 @@ describe('$mdDateLocale', function() {
  expect(dateLocale.parseDate(dateStr)).toEqual(jasmine.any(Date));
  });
 
+ it('should default to the US date formatting', function() {
+ var date = new Date(2014, 2, 25);
+ var dateStr = dateLocale.formatDate(date);
+ expect(dateStr).toBe('3/25/2014');
+ });
+
  it('should have default date completion detection', function() {
  // Valid dates.
  expect(dateLocale.isDateComplete('04/05/15')).toBe(true);

src/components/datepicker/dateLocaleProvider.js

@@ -149,7 +149,7 @@
  * @param $locale
  * @returns {DateLocale}
  */
- DateLocaleProvider.prototype.$get = function($locale) {
+ DateLocaleProvider.prototype.$get = function($locale, $filter) {
  /**
  * Default date-to-string formatting function.
  * @param {!Date} date
@@ -172,7 +172,7 @@
  formatDate = new Date(date.getFullYear(), date.getMonth(), date.getDate(), 1, 0, 0);
  }
 
- return formatDate.toLocaleDateString();
+ return $filter('date')(formatDate, 'M/d/yyyy');
  }
 
  /**