Rewrite build_pkgs.sh and build_test_pkgs.sh in Dart.

Rewrite build_pkgs.sh and build_test_pkgs.sh in Dart.

The bots need to run these before running the tests, so I'm porting them
to Dart so they'll run on Windows.

As a nice bonus, they're much faster now, I'm assuming because we use
one warmed up VM for all of the packages.

build_test_pkgs.sh on my machine went from ~12 seconds to ~4.

R=jmesserly@google.com, vsm@google.com

Committed: https://github.com/dart-lang/sdk/commit/926df1e5b3086fe79789a66be309bd638c94a111

[Bob Nystrom, 2016-11-12 02:20:07]

rnystrom@google.com changed reviewers:
+ jmesserly@google.com, vsm@google.com

[vsm, 2016-11-14 17:39:41]

lgtm

I think we can probably redo build_pkgs.dart and discover the right structure
and just list exceptions (force-compile/broken targets).  It might be painful
keeping this up-to-date (true with the sh version too).

[Jennifer Messerly, 2016-11-14 18:52:24]

LGTM!

[Bob Nystrom, 2016-11-15 19:14:40]

Description was changed from

==========
Rewrite build_pkgs.sh and build_test_pkgs.sh in Dart.

The bots need to run these before running the tests, so I'm porting them
to Dart so they'll run on Windows.

As a nice bonus, they're much faster now, I'm assuming because we use
one warmed up VM for all of the packages.

build_test_pkgs.sh on my machine went from ~12 seconds to ~4.
==========

to

==========
Rewrite build_pkgs.sh and build_test_pkgs.sh in Dart.

The bots need to run these before running the tests, so I'm porting them
to Dart so they'll run on Windows.

As a nice bonus, they're much faster now, I'm assuming because we use
one warmed up VM for all of the packages.

build_test_pkgs.sh on my machine went from ~12 seconds to ~4.

R=jmesserly@google.com, vsm@google.com

Committed:
https://github.com/dart-lang/sdk/commit/926df1e5b3086fe79789a66be309bd638c94a111
==========

[Bob Nystrom, 2016-11-15 19:14:41]

Committed patchset #1 (id:1) manually as
926df1e5b3086fe79789a66be309bd638c94a111 (presubmit successful).