fix($locale): Allow currency filter to fall back to maxFrac from locale

- Modify default fallback to `NUMBER_FORMATS.PATTERNS[1].maxFrac`

- Remove unnecessary resetting

Closes #10179

src/ng/filter/filters.js

@@ -11,7 +11,7 @@
  *
  * @param {number} amount Input to filter.
  * @param {string=} symbol Currency symbol or identifier to be displayed.
- * @param {number=} fractionSize Number of decimal places to round the amount to.
+ * @param {number=} fractionSize Number of decimal places to round the amount to, defaults to default max fraction size for current locale
  * @returns {string} Formatted number.
  *
  *
@@ -61,8 +61,7 @@ function currencyFilter($locale) {
     }
 
     if (isUndefined(fractionSize)) {
-      // TODO: read the default value from the locale file
-      fractionSize = 2;
+      fractionSize = formats.PATTERNS[1].maxFrac;
     }
 
     // if null or undefined pass it through

test/ng/filter/filtersSpec.js

@@ -120,6 +120,12 @@ describe('filters', function() {
       expect(currency(0.008)).toBe('$0.01');
       expect(currency(0.003)).toBe('$0.00');
     });
+
+    it('should set the default fraction size to the max fraction size of the locale value', inject(function($locale) {
+      $locale.NUMBER_FORMATS.PATTERNS[1].maxFrac = 1;
+
+      expect(currency(1.07)).toBe('$1.1');
+    }));
   });