Delete kotlin.jvm.internal.KObject

It was supposed to be used in reflection but the benefits do not outweigh the
cost of KT-6951

 #KT-3223 Fixed
 #KT-6951 Fixed

compiler/testData/classpathOrder/classpathOrder.kt

@@ -1,12 +1,12 @@
 package test
 
-import kotlin.jvm.internal.KObject
 import kotlin.jvm.internal.Intrinsics
+import kotlin.jvm.internal.Ref
 
 fun foo(): String {
     // This method call should be resolved to kotlin-runtime.jar
     val r: String = Intrinsics.stringPlus(":", ")")
 
     // This method call should be resolved to sources
-    return KObject.methodWhichDoesNotExistInKotlinRuntime()
+    return Ref.methodWhichDoesNotExistInKotlinRuntime()
 }

compiler/testData/classpathOrder/kotlin/jvm/internal/Ref.java

@@ -1,6 +1,6 @@
 package kotlin.jvm.internal;
 
-public class KObject {
+public class Ref {
     public static String methodWhichDoesNotExistInKotlinRuntime() {
         return ":)";
     }