scala: Revert "update from 2.11.1 to 2.11.3".

This reverts commit 4507aeb20015979d85e4df2610c8d00969173e2c.
Scala 2.11.3 is broken:

  https://groups.google.com/forum/#!msg/scala-internals/SSD9BNJaFbU/rACBkHrs2JEJ.