More improvements to DeclarationResolver.

More improvements to DeclarationResolver.

This CL makes the following improvements:

- When visiting an executable element, local variables and labels are
  rebuilt rather than matching them up to the old element model.  This
  ensures that if the element model was resynthesized from an API
  summary (which doesn't contain local variables or labels), these
  elements are not lost.

- When matching up existing elements, if the elements did not
  previously contain offsets, offsets are recorded.  If they did
  previously contain offsets, the offsets are compared to verify that
  they match.  This ensures that if the element model was
  resynthesized from an API summary (which doesn't contain offsets),
  the offsets will be correct.

R=brianwilkerson@google.com, scheglov@google.com

Committed: https://github.com/dart-lang/sdk/commit/396d7862b4e3c4bf5dfa87927301d884503b0557

[Paul Berry, 2016-10-21 16:55:18]

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

[Brian Wilkerson, 2016-10-21 17:52:24]

lgtm

[scheglov, 2016-10-21 17:54:43]

LGTM

[Paul Berry, 2016-10-21 18:14:00]

Description was changed from

==========
More improvements to DeclarationResolver.

This CL makes the following improvements:

- When visiting an executable element, local variables and labels are
  rebuilt rather than matching them up to the old element model.  This
  ensures that if the element model was resynthesized from an API
  summary (which doesn't contain local variables or labels), these
  elements are not lost.

- When matching up existing elements, if the elements did not
  previously contain offsets, offsets are recorded.  If they did
  previously contain offsets, the offsets are compared to verify that
  they match.  This ensures that if the element model was
  resynthesized from an API summary (which doesn't contain offsets),
  the offsets will be correct.
==========

to

==========
More improvements to DeclarationResolver.

This CL makes the following improvements:

- When visiting an executable element, local variables and labels are
  rebuilt rather than matching them up to the old element model.  This
  ensures that if the element model was resynthesized from an API
  summary (which doesn't contain local variables or labels), these
  elements are not lost.

- When matching up existing elements, if the elements did not
  previously contain offsets, offsets are recorded.  If they did
  previously contain offsets, the offsets are compared to verify that
  they match.  This ensures that if the element model was
  resynthesized from an API summary (which doesn't contain offsets),
  the offsets will be correct.

R=brianwilkerson@google.com, scheglov@google.com

Committed:
https://github.com/dart-lang/sdk/commit/396d7862b4e3c4bf5dfa87927301d884503b0557
==========

[Paul Berry, 2016-10-21 18:14:01]

Committed patchset #1 (id:1) manually as
396d7862b4e3c4bf5dfa87927301d884503b0557 (presubmit successful).