Extract BuilderContext from ASTEmitter

BUG=
R=sigurdm@google.com

Review URL: https://codereview.chromium.org//763993002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@42034 260f80e4-7a28-3924-810f-c04153c831b5
Disable super-aliases during incremental compilation.

R=herhut@google.com, johnniwinther@google.com

Review URL: https://codereview.chromium.org//762793002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@42035 260f80e4-7a28-3924-810f-c04153c831b5
Always enable RTI for incremental compilation.

R=johnniwinther@google.com

Review URL: https://codereview.chromium.org//755223002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@42036 260f80e4-7a28-3924-810f-c04153c831b5
Avoid checking for uses in try-blocks, when optimizing a function without try-catch.

R=zerny@google.com

Review URL: https://codereview.chromium.org//760013002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@42037 260f80e4-7a28-3924-810f-c04153c831b5