ClassfileParser: avoid looking up inner class in wrong phase

getMember needs to take an implicit `Context` parameter, otherwise the
following code:
  val result = ctx.atPhaseNotLaterThan(ctx.typerPhase) { implicit ctx =>
    getMember(owner, innerName.toTypeName)
  }
will not run getMember at the typer phase.

Author: smarter

compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala

@@ -806,7 +806,7 @@ class ClassfileParser(
     def classSymbol(externalName: Name)(implicit ctx: Context): Symbol = {
       /** Return the symbol of `innerName`, having the given `externalName`. */
       def innerSymbol(externalName: Name, innerName: Name, static: Boolean): Symbol = {
-        def getMember(sym: Symbol, name: Name): Symbol =
+        def getMember(sym: Symbol, name: Name)(implicit ctx: Context): Symbol =
           if (static)
             if (sym == classRoot.symbol) staticScope.lookup(name)
             else sym.companionModule.info.member(name).symbol