Test runner: Detect extra property in 'actual' but not in 'expected'. (#407)

* Test runner: Detect extra property in 'actual' but not in 'expected'.

Also update all expected.json where this would result in errors.

* Include rmExpected.js script in case it is needed again

test/fixtures/esprima/es2015-array-pattern/empty-pattern-lexical/expected.json

@@ -93,6 +93,7 @@
         ],
         "kind": "let"
       }
-    ]
+    ],
+    "directives": []
   }
 }