Fix warnings in pkg/analyzer caused by be6a822daff2fae75a480d7da656ab0d9c86512e

Fix warnings in pkg/analyzer caused by be6a822daff2fae75a480d7da656ab0d9c86512e

Dart's type promotion rules aren't sophisticated enough to understand
that (a is num && b is num) || (a is String && b is String) means that
it is safe to evaluate (a + b), so we have to split it into two
separate cases.

TBR=mfairhurst@google.com,scheglov@google.com

Committed: https://github.com/dart-lang/sdk/commit/2805019038c52e33b15d6046a83ce3166dda94f3

[Paul Berry, 2016-12-25 16:00:51]

Description was changed from

==========
Fix warnings in pkg/analyzer caused by be6a822daff2fae75a480d7da656ab0d9c86512e

Dart's type promotion rules aren't sophisticated enough to understand
that (a is num && b is num) || (a is String && b is String) means that
it is safe to evaluate (a + b), so we have to split it into two
separate cases.

TBR=mfairhurst@google.com,scheglov@google.com
==========

to

==========
Fix warnings in pkg/analyzer caused by be6a822daff2fae75a480d7da656ab0d9c86512e

Dart's type promotion rules aren't sophisticated enough to understand
that (a is num && b is num) || (a is String && b is String) means that
it is safe to evaluate (a + b), so we have to split it into two
separate cases.

TBR=mfairhurst@google.com,scheglov@google.com

Committed:
https://github.com/dart-lang/sdk/commit/2805019038c52e33b15d6046a83ce3166dda94f3
==========

[Paul Berry, 2016-12-25 16:00:53]

Committed patchset #1 (id:1) manually as
2805019038c52e33b15d6046a83ce3166dda94f3 (presubmit successful).

[scheglov, 2016-12-25 19:24:02]

LGTM

[mfairhurst, 2016-12-27 20:16:22]

lgtm

Good catch, thanks for fixing my mistake here!