NATIVE_JSON indicates whether the code should rely on the
native JSON
functions, if available.
The JSON functions can be defined by external libraries like Prototype
and setting this flag to false forces the use of Closure's goog.json
implementation.
If your JavaScript can be loaded by a third_party site and you are wary
about relying on the native functions, specify
"--define bot.json.NATIVE_JSON=false" to the Closure compiler.