This option enables/disables the results cache in generated parsers.
Until now, it was always enabled, but after this commit it needs to be
enabled explicitly (i.e. the |cache| option default value is |false|).
The reason is that parsing without it is *much* faster according to the
benchmark.
Note that disabling the cache breaks the linear parsing time guarantee,
meaning that with some grammars you can get exponential parsing time
with respect to the input length. This, together with the possibility of
improving the cache performance in the future, is the reason to keep it
as an option.
Speed impact
------------
Before: 214.08 kB/s
After: 827.52 kB/s
Difference: 286.54%
Size impact
-----------
Before: 1045396 b
After: 949783 b
Difference: -9.15%
(Measured by /tools/impact with Node.js v0.6.6 on x86_64 GNU/Linux.)