Remove outdated doc

Author: EugeneFlesselle

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -4641,10 +4641,6 @@ object Types extends TypeUtils {
         case nil => x
       foldArgs(op(x, tycon), args)
 
-    /** Exists if the tycon is a TypeRef of an alias with an underlying match type.
-     *  Anything else should have already been reduced in `appliedTo` by the TypeAssigner.
-     *  May reduce several HKTypeLambda applications before the underlying MatchType is reached.
-     */
     override def underlyingNormalizable(using Context): Type =
       if ctx.period != validUnderlyingNormalizable then
         validUnderlyingNormalizable = if tycon.isProvisional then Nowhere else ctx.period
@@ -4654,7 +4650,7 @@ object Types extends TypeUtils {
       cachedUnderlyingNormalizable
 
     override def tryNormalize(using Context): Type =
-      if MatchTypeTrace.isRecording && isMatchAlias then
+      if isMatchAlias && MatchTypeTrace.isRecording then
         MatchTypeTrace.recurseWith(this)(superType.tryNormalize)
       else super.tryNormalize