Support assignment of locals in analyzer2dart.

BUG=
R=paulberry@google.com

Review URL: https://codereview.chromium.org//652403005

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41352 260f80e4-7a28-3924-810f-c04153c831b5
Revert "Make stdout/stderr async"

This reverts r41350.

There are test-failures that needs to be analyzed.

TBR=iposva@google.com, ajohnsen@google.com
BUG=

Review URL: https://codereview.chromium.org//686703002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41353 260f80e4-7a28-3924-810f-c04153c831b5