fix(repeat): Apply $last to the array after $properties have been filtered out

If the $last property is calculated from the original collectionLength on an object and properties starting with $ were filtered out, then $last is never applied and $middle is applied erroniously.
This fix uses the length of the filtered array instead.

Fixes angular#1789

Author: petebacondarwin

src/ng/directive/ngRepeat.js

@@ -149,7 +149,7 @@ var ngRepeatDirective = ngDirective({
           childScope.$index = index;
 
           childScope.$first = (index === 0);
-          childScope.$last = (index === (collectionLength - 1));
+          childScope.$last = (index === (array.length - 1));
           childScope.$middle = !(childScope.$first || childScope.$last);
 
           if (!last) {