Respect quote style in object literals

Respect quote style in object literals

The option added in fbbaa42ee55a7f753f7cab9b1a905ccf73cf26d5 wasn't
being respected inside object literals, so quoted property names would
still be stripped out with this option.

This is mostly a corner-case, but useful when the output is passed to
something like the Closure compiler, where quoted property names can be
used to prevent mangling.