Minor: move property from UnusedSymbolInspection to ktPsiUtil

compiler/psi/src/org/jetbrains/kotlin/psi/psiUtil/ktPsiUtil.kt

@@ -428,6 +428,8 @@ val KtStringTemplateExpression.plainContent: String
 
 fun KtStringTemplateExpression.isSingleQuoted(): Boolean = node.firstChildNode.textLength == 1
 
+val KtNamedDeclaration.isPrivateNestedClassOrObject: Boolean get() = this is KtClassOrObject && isPrivate() && !isTopLevel()
+
 fun KtNamedDeclaration.getValueParameters(): List<KtParameter> {
     return getValueParameterList()?.parameters ?: Collections.emptyList()
 }

idea/src/org/jetbrains/kotlin/idea/inspections/UnusedSymbolInspection.kt

@@ -518,8 +518,6 @@ class SafeDeleteFix(declaration: KtDeclaration) : LocalQuickFix {
     }
 }
 
-private val KtNamedDeclaration.isPrivateNestedClassOrObject: Boolean get() = this is KtClassOrObject && isPrivate() && !isTopLevel()
-
 private fun safeDelete(project: Project, declaration: PsiElement) {
     if (declaration is KtNamedDeclaration && declaration.isPrivateNestedClassOrObject) {
         runWriteAction {