Speed up markdown parsing with fast path for plain words.

Speed up markdown parsing with fast path for plain words.

This takes the apidoc build step time on my (old) machine down by a
third from 67s to 43s.

Committed: https://code.google.com/p/dart/source/detail?r=13429

[sra1, 2012-10-09 01:22:07]

Hi Johnni,

This is a small change to speed up apidoc.

I also noticed some SSA code in the profile.  Do you know if unnecessary dart2js
passes might be slowing down apidoc?

[Johnni Winther, 2012-10-09 07:46:41]

On 2012/10/09 01:22:07, sra1 wrote:
> Hi Johnni,
> 
> This is a small change to speed up apidoc.
> 
> I also noticed some SSA code in the profile.  Do you know if unnecessary
dart2js
> passes might be slowing down apidoc?

Dart2js is slowing it down because it does to much work on the code. We have no
pipeline for just doing the analysis of the code exterior so some unneeded work
is done.

[Johnni Winther, 2012-10-09 07:47:27]

lgtm