Allow opaque type def in repl

Author: noti0na1

Diff for: compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -4696,6 +4696,8 @@ object Parsers {
           stats += closure(in.offset, Location.InBlock, modifiers(BitSet(IMPLICIT)))
         else if isIdent(nme.extension) && followingIsExtension() then
           stats += extension()
+        else if ctx.mode.is(Mode.Interactive) && isDefIntro(localModifierTokens) then
+          stats +++= localDef(in.offset)
         else if isDefIntro(localModifierTokens, excludedSoftModifiers = Set(nme.`opaque`)) then
           stats +++= localDef(in.offset)
         else