fix(orderBy): support string predicates containing non-ident characters

The orderBy filter now allows string predicates passed to the orderBy filter to make use property
name predicates containing non-ident strings, such as spaces or percent signs, or non-latin
characters.

This behaviour requires the predicate string to be double-quoted.

In markup, this might look like so:

```html
<div ng-repeat="item in items | orderBy:'\"Tip %\"'">
...
</div>
```

Or in JS:

```js
var sorted = $filter('orderBy')(array, ['"Tip %"', '-"Subtotal $"'], false);
```

Closes angular#6143

src/ng/filter/orderBy.js

@@ -62,17 +62,30 @@
  */
 orderByFilter.$inject = ['$parse'];
 function orderByFilter($parse){
+  var QUOTED_STRING_REGEXP = /^\s*(['"])([^'"]*)(['"])\s*$/;
   return function(array, sortPredicate, reverseOrder) {
+    var locals;
     if (!isArray(array)) return array;
     if (!sortPredicate) return array;
     sortPredicate = isArray(sortPredicate) ? sortPredicate: [sortPredicate];
     sortPredicate = map(sortPredicate, function(predicate){
-      var descending = false, get = predicate || identity;
+      var descending = false, get = predicate || identity, match;
       if (isString(predicate)) {
         if ((predicate.charAt(0) == '+' || predicate.charAt(0) == '-')) {
           descending = predicate.charAt(0) == '-';
           predicate = predicate.substring(1);
         }
+        if ((match = predicate.match(QUOTED_STRING_REGEXP)) && match[1] === match[3]) {
+          // If the predicate is a quoted string, it might contain special characters, and requires
+          // a different getter expression to work correctly.
+          locals = locals || {item: null};
+          get = $parse('item["'+match[2]+'"]');
+          return reverseComparator(function(a,b) {
+            locals.item = a, a = get(a, locals), locals.item = b, b = get(b, locals);
+            return compare(a, b);
+          }, descending);
+        }
+
         get = $parse(predicate);
       }
       return reverseComparator(function(a,b){

test/ng/filter/orderBySpec.js

@@ -31,4 +31,10 @@ describe('Filter: orderBy', function() {
     toEqual([{a:2, b:1},{a:15, b:1}]);
   });
 
+  it('should support string predicates with names containing non-identifier characters', function() {
+    expect(orderBy([{"Tip %": .25}, {"Tip %": .15}, {"Tip %": .40}], '"Tip %"'))
+      .toEqualData([{"Tip %": .15}, {"Tip %": .25}, {"Tip %": .40}]);
+    expect(orderBy([{"원": 76000}, {"원": 31000}, {"원": 156000}], '"원"'))
+      .toEqualData([{"원": 31000}, {"원": 76000}, {"원": 156000}])
+  });
 });