Fix simpleCaseObject.decompiled and add regression test

Author: nicolasstucki

tests/pos/simpleCaseObject.decompiled

@@ -1,7 +1,6 @@
 /** Decompiled from out/posTestFromTasty/pos/simpleCaseObject/foo/Foo.tasty */
 package foo {
   case object Foo {
-    def writeReplace(): scala.AnyRef = new scala.runtime.ModuleSerializationProxy(classOf[foo.Foo])
     override def hashCode(): scala.Int = 1045991777
     override def toString(): java.lang.String = "Foo"
     override def canEqual(that: scala.Any): scala.Boolean = that.isInstanceOf[foo.Foo.type @scala.unchecked()]
@@ -12,4 +11,4 @@ package foo {
         throw new java.lang.IndexOutOfBoundsException(n.toString())
     }
   }
-}
+}

tests/run/classof-object.decompiled

@@ -0,0 +1,4 @@
+/** Decompiled from out/runTestFromTasty/run/classof-object/Test.tasty */
+object Test {
+  def main(args: scala.Array[scala.Predef.String]): scala.Unit = if (scala.Predef.classOf[Test.type].==(Test.getClass()).unary_!) dotty.DottyPredef.assertFail() else ()
+}