Remove the need for functionSignature.

BUG=
R=floitsch@google.com

Review URL: https://codereview.chromium.org//641923003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41067 260f80e4-7a28-3924-810f-c04153c831b5
Refactor tracking of instantiated types/classes.

BUG=
R=floitsch@google.com

Review URL: https://codereview.chromium.org//645613003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41068 260f80e4-7a28-3924-810f-c04153c831b5