Address some of dotty deviations in backend.

Implicit vals need explicit type, anonymous classes are widened.

Author: DarkDimius

src/dotty/tools/backend/jvm/LabelDefs.scala

@@ -164,7 +164,7 @@ class LabelDefs extends MiniPhaseTransform {
     }
   }
 
-  val collectLabelDefs = new TreeMap() {
+  object collectLabelDefs extends TreeMap() {
 
     // label calls from this DefDef
     var parentLabelCalls: mutable.Set[Tree] = new mutable.HashSet[Tree]()

src/dotty/tools/backend/jvm/scalaPrimitives.scala

@@ -125,7 +125,7 @@ class DottyPrimitives(ctx: Context) {
   /** Initialize the primitive map */
   private def init: immutable.Map[Symbol, Int]  = {
 
-    implicit val ctx = this.ctx
+    implicit val ctx: Context = this.ctx
 
     import core.Symbols.defn
     val primitives = new mutable.HashMap[Symbol, Int]()