Fix analyzer error

Fix analyzer error

Analyzer was complaining that final field was not set.  The other constructor
does set, so doing so here as well.  We may be able to remove this flag soon,
but I see downstream uses.

TBR=jmesserly@google.com

Committed: https://github.com/dart-lang/dev_compiler/commit/6144c10409c4285ec24a1eaa4d31699b874c301b

[vsm, 2016-09-28 17:21:20]

Description was changed from

==========
Fix analyzer error

Analyzer was complaining that final field was not set.  The other constructor
does set, so doing so here as well.  We may be able to remove this flag soon,
but I see downstream uses.

TBR=jmesserly@google.com
==========

to

==========
Fix analyzer error

Analyzer was complaining that final field was not set.  The other constructor
does set, so doing so here as well.  We may be able to remove this flag soon,
but I see downstream uses.

TBR=jmesserly@google.com

Committed:
https://github.com/dart-lang/dev_compiler/commit/6144c10409c4285ec24a1eaa4d31...
==========

[vsm, 2016-09-28 17:21:21]

Committed patchset #1 (id:1) manually as
6144c10409c4285ec24a1eaa4d31699b874c301b (presubmit successful).

[Jennifer Messerly, 2016-09-28 17:49:05]

lgtm. no big deal on the style issue, just an FYI

https://codereview.chromium.org/2382463002/diff/1/pkg/dev_compiler/lib/src/an...
File pkg/dev_compiler/lib/src/analyzer/context.dart (right):

https://codereview.chromium.org/2382463002/diff/1/pkg/dev_compiler/lib/src/an...
pkg/dev_compiler/lib/src/analyzer/context.dart:54: this.packageRoot: null,
style nit: ": null" part is not needed.

you do need "this.packageRoot," though :)