Add missing type and import for 2.12 build

Author: nicolasstucki

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -1017,7 +1017,7 @@ object desugar {
       var tested: MemberDef = tree
       def fail(msg: String) = ctx.error(msg, tree.sourcePos)
       def checkApplicable(flag: FlagSet, test: MemberDefTest): Unit =
-        if (tested.mods.is(flag) && !test.applyOrElse(tree, _ => false)) {
+        if (tested.mods.is(flag) && !test.applyOrElse(tree, (md: MemberDef) => false)) {
           fail(i"modifier `$flag` is not allowed for this definition")
           tested = tested.withMods(tested.mods.withoutFlags(flag))
         }

compiler/src/dotty/tools/dotc/core/Annotations.scala

@@ -181,6 +181,7 @@ object Annotations {
     object WithBounds {
       def unapply(ann: Annotation)(implicit ctx: Context): Option[TypeBounds] =
         if (ann.symbol == defn.WithBoundsAnnot) {
+          import ast.Trees._
           // We need to extract the type of the type tree in the New itself.
           // The annotation's type has been simplified as the type of an expression,
           // which means that `&` or `|` might have been lost.