Bug 1618620 - generate_bookmarks.py can already run in py3; r=firefox-build-system-reviewers,rstewart

This was blocked on the preprocessor, which was fixed in bug 1613263.

Differential Revision: https://phabricator.services.mozilla.com/D64619

--HG--
extra : moz-landing-system : lando

browser/locales/moz.build

@@ -34,7 +34,6 @@ bookmarks.inputs = [
     # The `locales/en-US/` will be rewritten to the locale-specific path.
     'en-US/profile/bookmarks.inc',
 ]
-bookmarks.py2 = True
 
 with Files("**"):
     BUG_COMPONENT = ("Firefox Build System", "General")