Simplify literals dumping and reduce size

Saved 3.2% size (3.5k) in jquery size benchmark.

Inline PROP keys.
Inline MEMBER keys.
Anonymous functions take a NOP, instead of a dummy "?" identifier.

Remove duplication in member and index handling among `new` and
`call` productions.
Merge pull request #72 from cesanta/ast_opts

Simplify literals dumping and reduce size