Refactor parsing object members (#9607)

* Refactor parsing object members

* Ensure decorators on rest don’t swallow decorators silently

* Use hasPrecedingLineBreak

* Add test for async with linebreak

* Update flow whitelist

scripts/tests/test262/run_babel_parser_test262_utils.js

@@ -229,7 +229,7 @@ exports.updateWhitelist = function(filename, summary) {
         return line;
       })
       .filter(function(line) {
-        return line !== null;
+        return line !== null && line !== "";
       })
       .concat(toAdd)
       .sort()