Add partial support for TryFinally and TryCatch statements

Add partial support for TryFinally and TryCatch statements

BUG=
R=dmitryas@google.com

Committed: https://github.com/dart-lang/sdk/commit/72ba4f6c1cb904ea325ea8b293ad6317a41c7f72

[zhivkag, 2017-08-03 07:17:08]

zhivkag@google.com changed reviewers:
+ dmitryas@google.com, kmillikin@google.com

[zhivkag, 2017-08-03 07:17:09]

This adds partial support for TryFinally and TryCatch by executing the bodies of
these statements. It lacks support for: 
- Executing the finalizer when a break is encountered in the TryFinally body to
an enclosing label, added in follow up CL. 
- Executing the corresponding catch clause when an exception is thrown in
TryCatch, which will be added after adding support for "is" expressions.

[Dmitry Stefantsov, 2017-08-03 09:15:52]

I like it!  LGTM.

[zhivkag, 2017-08-03 10:51:53]

Description was changed from

==========
Add partial support for TryFinally and TryCatch statements

BUG=
==========

to

==========
Add partial support for TryFinally and TryCatch statements

BUG=
R=dmitryas@google.com

Committed:
https://github.com/dart-lang/sdk/commit/72ba4f6c1cb904ea325ea8b293ad6317a41c7f72
==========

[zhivkag, 2017-08-03 10:51:54]

Committed patchset #3 (id:40001) manually as
72ba4f6c1cb904ea325ea8b293ad6317a41c7f72 (presubmit successful).