fix(parser/eval): fix for '"s" + ("m"|filter) + "e"'

closes dart-archive#755

Author: vicb

bin/parser_generator_for_spec.dart

@@ -175,6 +175,7 @@ main(arguments) {
       'add(a,b)',
       'notAProperty',
       "'Foo'|uppercase",
+      "'f' + ('o'|uppercase) + 'o'",
       "1|increment:2",
       "'abcd'|substring:1:offset",
       "'abcd'|substring:1:3|uppercase",

test/core/parser/parser_spec.dart

@@ -980,6 +980,7 @@ main() {
     describe('filters', () {
       it('should call a filter', () {
         expect(eval("'Foo'|uppercase", filters)).toEqual("FOO");
+        expect(eval("'f' + ('o'|uppercase) + 'o'", filters)).toEqual("fOo");
         expect(eval("'fOo'|uppercase|lowercase", filters)).toEqual("foo");
       });