reverses SI-6484

Unfortunately I have to revert b017629 because of SI-8303. There are projects
(e.g. slick) that use typeOf in annotations, which effectively means bye-bye.
makes sure compat._ provides full compatibility with 2.10.x

This is extremely important to enable cross-versioning Scala 2.10 codebases
against Scala 2.11 using Jason's trick with:

  // TODO 2.11 Remove this after dropping 2.10.x support.
  private object HasCompat { val compat = ??? }; import HasCompat._

  def impl(c: Context)(...): ... = {
    import c.universe._
    import compat._
    ...
  }