Adapt isPackageObject to semantic naming

Used a hardcoded string before, which caused test failures.

Author: odersky

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

@@ -135,7 +135,6 @@ object StdNames {
     val OPS_PACKAGE: N                = "<special-ops>"
     val OVERLOADED: N                 = "<overloaded>"
     val PACKAGE: N                    = "package"
-    val PACKAGE_CLS: N                = "package$"
     val ROOT: N                       = "<root>"
     val SPECIALIZED_SUFFIX: N         = "$sp"
     val SUPER_PREFIX: N               = "super$"

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

@@ -513,7 +513,7 @@ object SymDenotations {
 
     /** Is this symbol a package object or its module class? */
     def isPackageObject(implicit ctx: Context): Boolean = {
-      val poName = if (isType) nme.PACKAGE_CLS else nme.PACKAGE
+      val poName = if (isType) nme.PACKAGE.moduleClassName else nme.PACKAGE
       (name.toTermName == poName) && (owner is Package) && (this is Module)
     }