Turn optimisations for tests on again.

It turns out that when we restrict DropGoodCasts to
isInstanceOf tests (as opposed to pattern-matcher generated
type tests), we do not miss any error messages. Some warnings
are still be omitted under optimize, not sure whether we want
to fix that.

Author: odersky

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -288,7 +288,7 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
 
       def handlePositional(pnames: List[Name], args: List[Trees.Tree[T]]): List[Trees.Tree[T]] =
         args match {
-          case (arg: NamedArg) :: _ =>
+          case (arg: NamedArg @unchecked) :: _ =>
             val nameAssocs = for (arg @ NamedArg(name, _) <- args) yield (name, arg)
             handleNamed(pnames, args, nameAssocs.toMap, Set())
           case arg :: args1 => arg :: handlePositional(pnames.tail, args1)

compiler/test/dotty/tools/vulpix/TestConfiguration.scala

@@ -54,7 +54,7 @@ object TestConfiguration {
 
   val defaultUnoptimised = noCheckOptions ++ checkOptions ++ yCheckOptions ++ classPath
   val defaultOptimised = defaultUnoptimised :+ "-optimise"
-  val defaultOptions = defaultUnoptimised
+  val defaultOptions = defaultOptimised
   val allowDeepSubtypes = defaultOptions diff Array("-Yno-deep-subtypes")
   val allowDoubleBindings = defaultOptions diff Array("-Yno-double-bindings")
   val picklingOptions = defaultUnoptimised ++ Array(