Add BUILD.gn for pkg/front_end to fix the Fuchsia build

Add BUILD.gn for pkg/front_end to fix the Fuchsia build

BUG=
R=paulberry@google.com

Committed: https://github.com/dart-lang/sdk/commit/5f8580a6738187c299797d573214b5a87b7144e4

[ianloic, 2016-11-08 22:46:28]

ianloic@google.com changed reviewers:
+ abarth@google.com, paulberry@google.com, zra@google.com

[Paul Berry, 2016-11-08 22:48:35]

lgtm

[zra, 2016-11-08 22:52:12]

I wonder if these package build files should be in Fuchsia's //build/secondary
since they are unrelated to anything we build out of the Dart tree.

[ianloic, 2016-11-08 23:06:15]

I apparently don't have permission to land this on github :(

[ianloic, 2016-11-08 23:11:30]

+lanechr FYI

[zra, 2016-11-08 23:15:10]

Description was changed from

==========
Add BUILD.gn for pkg/front_end to fix the Fuchsia build

BUG=
==========

to

==========
Add BUILD.gn for pkg/front_end to fix the Fuchsia build

BUG=
R=paulberry@google.com

Committed:
https://github.com/dart-lang/sdk/commit/5f8580a6738187c299797d573214b5a87b7144e4
==========

[zra, 2016-11-08 23:15:11]

Committed patchset #2 (id:20001) manually as
5f8580a6738187c299797d573214b5a87b7144e4 (presubmit successful).