scala/async — pull request #69 by retronym (2014-03-27 13:53:00+00:00)
Title: [backport] Allow lazy vals without await in the initializer

We were incorrectly typechecking the `ClassDef` of the state machine
in the macro in a way that discarded the resulting trees, and only
kept around the symbol.

The led to the the macro engine retypechecking
that node, which somehow led to duplicated lazy val initiaializer
`DefDef`-s in the template, which manifest as a `VerifyError`.

This commit:

- rescues the typechecked `ClassDef` node from the eager
typechecking by the macro
- loosens the restriction on lazy vals in async blocks. They are
still prohibited if they contain an await on the RHS
- Adds a test that shows evalution is indeed lazy.

(cherry picked from commit cc4587b1985519f7049d0feb0783d8e22c10f792)

Conflicts:
src/main/scala/scala/async/internal/AsyncAnalysis.scala
src/main/scala/scala/async/internal/AsyncTransform.scala

Review by @phaller