Remove Perl cruft from IDL compiler front end (mostly JSON export)

Mostly just remove code: net -190 lines
(also group type classes together, and replace some None with False)

Further simplification is possible, as we no longer need classes for
enums and unions; will do in followup, b/c more involved.

BUG=345137
TBR=haraken

Review URL: https://codereview.chromium.org/185303013

git-svn-id: svn://svn.chromium.org/blink/trunk@168470 bbb929c8-8fbe-4397-9dbb-9b2b20218538