FirstTransform: simplify needsCompanion code

Author: DarkDimius

src/dotty/tools/dotc/transform/FirstTransform.scala

@@ -36,9 +36,13 @@ class FirstTransform extends MiniPhaseTransform with IdentityDenotTransformer wi
 
   private var needsCompanionPredicate: ClassSymbol => Boolean = null
 
+  private var addCompanionPhases: List[NeedsCompanions] = _
+
+  def needsCompanion(cls: ClassSymbol)(implicit ctx: Context) =
+    addCompanionPhases.exists(_.isCompanionNeeded(cls))
+
   override def prepareForUnit(tree: tpd.Tree)(implicit ctx: Context): TreeTransform = {
-    needsCompanionPredicate = ctx.phasePlan.flatMap(_.filter(x => x.isInstanceOf[NeedsCompanions])).
-      foldLeft((x: ClassSymbol) => false)((pred, phase) => x => pred(x) || phase.asInstanceOf[NeedsCompanions].isCompanionNeeded(x))
+    addCompanionPhases = ctx.phasePlan.flatMap(_ collect { case p: NeedsCompanions => p })
     this
   }