Survive breakage in requiredMethod

But give more diagniostics what went wrong.

Author: odersky

src/dotty/tools/dotc/core/Denotations.scala

@@ -213,7 +213,10 @@ object Denotations {
         val meth = info.member(name.toTermName)
         if (meth.exists) meth.requiredSymbol(_ is Method).asTerm
         else { // Heisenbughunt
-          println(s"*** missing method: ${name.toString} in $this")
+          println(s"*** missing method: ${name.toTermName} in $this")
+          val lookedUp = info.decls.lookup(name.toTermName)
+          println(s"looked up: $lookedUp")
+          if (lookedUp.exists) return lookedUp.asTerm
           info.decls.checkConsistent()
           println(i"decls = ${info.decls}")
           if (slowSearch(name.toTermName).exists) {