Passing the context is not necessary, global variable is good enough
(passing the context would make more sense if each AST node was
translated into a function call, but this isn't the case).
The performance gain is very small, on the border of statstical error.
Results of benchmark with 100 runs on V8:
Before: 31.49 kB/s
After: 31.57 kB/s
Speedup: 0.254 %
Mozilla/5.0 (X11; U; Linux i686; en-US) AppleWebKit/533.4 (KHTML, like
Gecko) Chrome/5.0.375.127 Safari/533.4
The source code is now in the src directory. The library needs to be
built using "rake", which creates the lib/peg.js file by combining the
source files.
