Clean up handling of declared/inferred types in VariableElementForLink

Clean up handling of declared/inferred types in VariableElementForLink

This eliminates duplicate logic between VariableElementForLink and its
derived class FieldElementForLink_ClassField, and makes the logic in
these two classes more similar to the inferred type logic in
ExecutableElementForLink.  A few corner cases that were previously
broken are now fixed (and tested).

R=scheglov@google.com

Committed: https://github.com/dart-lang/sdk/commit/bc67d03e2172c722037f1bb08bf568d464dedc8f

[Paul Berry, 2016-04-19 18:44:12]

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

[scheglov, 2016-04-19 18:55:42]

LGTM

[Paul Berry, 2016-04-19 19:07:40]

Description was changed from

==========
Clean up handling of declared/inferred types in VariableElementForLink

This eliminates duplicate logic between VariableElementForLink and its
derived class FieldElementForLink_ClassField, and makes the logic in
these two classes more similar to the inferred type logic in
ExecutableElementForLink.  A few corner cases that were previously
broken are now fixed (and tested).
==========

to

==========
Clean up handling of declared/inferred types in VariableElementForLink

This eliminates duplicate logic between VariableElementForLink and its
derived class FieldElementForLink_ClassField, and makes the logic in
these two classes more similar to the inferred type logic in
ExecutableElementForLink.  A few corner cases that were previously
broken are now fixed (and tested).

R=scheglov@google.com

Committed:
https://github.com/dart-lang/sdk/commit/bc67d03e2172c722037f1bb08bf568d464dedc8f
==========

[Paul Berry, 2016-04-19 19:07:41]

Committed patchset #1 (id:1) manually as
bc67d03e2172c722037f1bb08bf568d464dedc8f (presubmit successful).