Fix constant evaluation dependency analysis for const external factories.

Fix constant evaluation dependency analysis for const external factories.

With the current constant evaluator, the bug is benign because we only
do dependency analysis within a library cycle, and the library cycle
containing dart:core (which is the only library cycle with const
external factories) contains no invocations of those const external
factories.

But in the new task model we do full dependency analysis across
library cycles, so the dependency analysis needs to be correct in
order for the const external factory to be safely invoked.

R=scheglov@google.com

Committed: https://github.com/dart-lang/sdk/commit/eb6d1e2579710409c1e6d5704fb621a9934f4625

[Paul Berry, 2015-05-18 20:11:19]

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

[Paul Berry, 2015-05-18 20:11:20]

This should fix the exception you emailed about on Friday.

[scheglov, 2015-05-18 20:14:19]

LGTM

[Paul Berry, 2015-05-18 20:18:37]

Committed patchset #1 (id:1) manually as
eb6d1e2579710409c1e6d5704fb621a9934f4625 (presubmit successful).