Set defTree properly

In the following test:

- tests/pos/i3130b.scala

If we add `transparent`, then everything is OK.
The reason is that we set `Symbol.defTree` systematically
in PostTyper. Now the inlining happens after PostTyper,
thus `defTree` is not properly set for inlined definitions.

To compensate, we ensure that `defTree` is set in the ReTyper.
The IninerTyper extends ReTyper, thus it fixes the problem.
Doing the fix directly in InlinerTyper, however, does not pass
the CI. The reason is that `-Ycheck:all` will run `TreeChecker`
which will make tree bindings get lost.

Author: liufengyun

compiler/src/dotty/tools/dotc/typer/ReTyper.scala

@@ -115,7 +115,9 @@ class ReTyper extends Typer with ReChecking {
   }
 
   override def typedUnadapted(tree: untpd.Tree, pt: Type, locked: TypeVars)(using Context): Tree =
-    try super.typedUnadapted(tree, pt, locked)
+    try super.typedUnadapted(tree, pt, locked) match
+      case member: MemberDef => member.setDefTree
+      case tree => tree
     catch {
       case NonFatal(ex) =>
         if ctx.phase != Phases.typerPhase && ctx.phase != Phases.inliningPhase then