Fix #9525: revert changes

Revert changes in e88c5b7

Author: liufengyun

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

@@ -1157,7 +1157,7 @@ object SymDenotations {
 
     final def scalacLinkedClass(using Context): Symbol =
       if (this.is(ModuleClass)) companionNamed(effectiveName.toTypeName)
-      else if (this.isClass) companionNamed(effectiveName.moduleClassName)
+      else if (this.isClass) companionNamed(effectiveName.moduleClassName).sourceModule.moduleClass
       else NoSymbol
 
     /** Find companion class symbol with given name, or NoSymbol if none exists.

compiler/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala

@@ -133,7 +133,7 @@ class Scala2Unpickler(bytes: Array[Byte], classRoot: ClassDenotation, moduleClas
   import Scala2Unpickler._
 
   val moduleRoot: SymDenotation = inContext(ictx) { moduleClassRoot.sourceModule.denot }
-  assert(moduleRoot.isTerm)
+  assert(moduleRoot.isTerm, "moduleRoot = " + moduleRoot + ", classRoot = " + classRoot + ", moduleClassRoot = " + moduleClassRoot)
 
   checkVersion(using ictx)