IR: fix mangling of toplevel properties

compiler/testData/codegen/boxInline/signatureMangling/indices.kt

@@ -0,0 +1,10 @@
+// TARGET_BACKEND: JVM_IR
+// WITH_RUNTIME
+// FILE: 1.kt
+inline fun inlineCallingIndices(): String {
+    val i1 = arrayOf("one", "two").indices
+    return "OK"
+}
+
+// FILE: 2.kt
+fun box() = inlineCallingIndices()