Fix constructor invocation type inference.

Fix constructor invocation type inference.

Three problems are fixed:

- I forgot to pass the `downwards` flag when doing downwards inference.

- I forgot to initialize the `formalTypes` and `actualTypes` arrays.

- I wasn't tracking whether constructor type arguments were implicit
  or explicit, so constructor type inference wasn't actually
  happening.

R=scheglov@google.com

Committed: https://github.com/dart-lang/sdk/commit/4eee6cb5ea554fe659de79a7883f103e781f2fb2

[Paul Berry, 2017-05-08 21:33:26]

paulberry@google.com changed reviewers:
+ ahe@google.com, scheglov@google.com

[scheglov, 2017-05-08 21:38:27]

LGTM

[Paul Berry, 2017-05-08 21:42:02]

Description was changed from

==========
Fix constructor invocation type inference.

Three problems are fixed:

- I forgot to pass the `downwards` flag when doing downwards inference.

- I forgot to initialize the `formalTypes` and `actualTypes` arrays.

- I wasn't tracking whether constructor type arguments were implicit
  or explicit, so constructor type inference wasn't actually
  happening.
==========

to

==========
Fix constructor invocation type inference.

Three problems are fixed:

- I forgot to pass the `downwards` flag when doing downwards inference.

- I forgot to initialize the `formalTypes` and `actualTypes` arrays.

- I wasn't tracking whether constructor type arguments were implicit
  or explicit, so constructor type inference wasn't actually
  happening.

R=scheglov@google.com

Committed:
https://github.com/dart-lang/sdk/commit/4eee6cb5ea554fe659de79a7883f103e781f2fb2
==========

[Paul Berry, 2017-05-08 21:42:03]

Committed patchset #3 (id:40001) manually as
4eee6cb5ea554fe659de79a7883f103e781f2fb2 (presubmit successful).