[IR] Use more specific type (IrSimpleFunction) for accessors in IrLocalDelegatedProperty

compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/declarations/impl/IrLocalDelegatedPropertyImpl.kt

@@ -1,17 +1,6 @@
 /*
- * Copyright 2010-2016 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.ir.declarations.impl
@@ -49,9 +38,9 @@ class IrLocalDelegatedPropertyImpl(
 
     override lateinit var delegate: IrVariable
 
-    override lateinit var getter: IrFunction
+    override lateinit var getter: IrSimpleFunction
 
-    override var setter: IrFunction? = null
+    override var setter: IrSimpleFunction? = null
 
     override var metadata: MetadataSource? = null
 }