Avoid double avoidance when typing blocks

For a Block, TypeAssigner does an avoid just for term symbols whereas
Typer does one for all local symbols. Since Typer called TypeAssigner,
we got a double avoidance pass. This is eliminated by assigning types
directly in Typer without passing through TypeAssigner.

Author: odersky

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

@@ -624,7 +624,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
       else pt.notApplied
     val expr1 = typedExpr(tree.expr, ept)(exprCtx)
     ensureNoLocalRefs(
-        assignType(cpy.Block(tree)(stats1, expr1), stats1, expr1), pt, localSyms(stats1))
+      cpy.Block(tree)(stats1, expr1).withType(expr1.tpe), pt, localSyms(stats1))
   }
 
   def escapingRefs(block: Tree, localSyms: => List[Symbol])(implicit ctx: Context): collection.Set[NamedType] = {