Support no-symbol on currency filter (closes #1131)

src/filters/index.js

@@ -61,7 +61,7 @@ var digitsRE = /(\d{3})(?=\d)/g
 exports.currency = function (value, currency) {
   value = parseFloat(value)
   if (!isFinite(value) || (!value && value !== 0)) return ''
-  currency = currency || '$'
+  currency = currency != null ? currency : '$'
   var stringified = Math.abs(value).toFixed(2)
   var _int = stringified.slice(0, -3)
   var i = _int.length % 3

test/unit/specs/filters/filters_spec.js

@@ -66,6 +66,8 @@ describe('Filters', function () {
     expect(filter(0.76)).toBe('$0.76')
     // sign arg
     expect(filter(2134, '@')).toBe('@2,134.00')
+    // no symbol
+    expect(filter(2134, '')).toBe('2,134.00')
     // falsy, infinity and 0
     expect(filter(0)).toBe('$0.00')
     expect(filter(false)).toBe('')