Return null script if stub tells us file is not a script

compiler/psi/src/org/jetbrains/kotlin/psi/KtFile.kt

@@ -96,6 +96,7 @@ open class KtFile(viewProvider: FileViewProvider, val isCompiled: Boolean) :
 
     val script: KtScript?
         get() {
+            stub?.let { if (!it.isScript()) return null }
             isScript?.let { if (!it) return null }
 
             val result = getChildOfType<KtScript>()