Avoid retraversing parts of the tree that do not contain Quote trees

Author: nicolasstucki

compiler/src/dotty/tools/dotc/transform/PickleQuotes.scala

@@ -100,8 +100,8 @@ class PickleQuotes extends MacroTransform {
       tree match
         case Apply(Select(quote: Quote, nme.apply), List(quotes)) =>
           val (contents, quote1) = makeHoles(quote)
-          val pickled = PickleQuotes.pickle(quote1, quotes, contents)
-          transform(pickled) // pickle quotes that are in the contents
+          val contents1 = contents.map(transform(_))
+          PickleQuotes.pickle(quote1, quotes, contents1)
         case tree: DefDef if !tree.rhs.isEmpty && tree.symbol.isInlineMethod =>
           // Shrink size of the tree. The methods have already been inlined.
           // TODO move to FirstTransform to trigger even without quotes