Merge branch 'sh-bump-whitequark-parser' into 'master'

Upgrade whitequark/parser to 2.5.3.0

See merge request gitlab-org/gitlab-ce!22652

Gemfile.lock

@@ -547,7 +547,7 @@ GEM
     orm_adapter (0.5.0)
     os (1.0.0)
     parallel (1.12.1)
-    parser (2.5.1.2)
+    parser (2.5.3.0)
       ast (~> 2.4.0)
     parslet (1.8.2)
     peek (1.0.1)