Don't special-case sealed

Author: Blaisorblade

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -1839,16 +1839,10 @@ object Parsers {
         val start = in.offset
         var mods = annotsAsMods()
         if (owner.isTypeName) {
-          mods = modifiers(start = mods)
+          // Adding ParamAccessor would crash
+          mods = modifiers(start = mods, allowed = modifierTokens &~ BitSet(SEALED)) | ParamAccessor
           if (mods.is(Lazy))
             syntaxError("`lazy' modifier not allowed here. Use call-by-name parameters instead")
-          mods =
-            if (mods.is(Sealed)) {
-              syntaxError("`sealed' modifier can be used only for classes")
-              mods // Adding ParamAccessor would crash
-            } else {
-              mods | ParamAccessor
-            }
           mods =
             atPos(start, in.offset) {
               if (in.token == VAL) {