Fix operator warning on 'Constr()()'

compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCallInInvokeCall.kt

@@ -1,10 +1,10 @@
 fun testInvoke() {
-    fun Nothing.invoke() = this
+    operator fun Nothing.invoke() = this
     todo()<!UNREACHABLE_CODE!>()<!>
 }
 
 fun testInvokeWithLambda() {
-    fun Nothing.invoke(<!UNUSED_PARAMETER!>i<!>: Int, f: () -> Int) = f
+    operator fun Nothing.invoke(<!UNUSED_PARAMETER!>i<!>: Int, f: () -> Int) = f
     todo()<!UNREACHABLE_CODE!>(1){ 42 }<!>
 }