The pub publish process was not following through with publishing
packages because the -f flag was not be provided to pub publish,
causing the process to prompt for confirmation before publishing,
which was causing the pub_publish.sh script to skip publishing.
Closes#3077
We have Dart code in `angular2` module that ought to be in its own
package. Examples include Dart analysis plugins, and potentially the
transformers (although transformers cannot be moved out just yet).
However, this code is Dart-only and it doesn’t make sense to use JS
directory layout for it. This commit introduces a sub-directory called
`modules_dart`. All modules in this directory are pure Dart packages
using standard pub directory layout. The code in these packages never
gets transpiled. It is directly copied to `dist` unmodified, except an
adjustment in relative paths in `pubspec.yaml` files.