Fix initialization of object's INSTANCE$ field

Call object's constructor in <clinit> and ignore the result, but in the first
line of <init> save the current "this" to INSTANCE$

 #KT-4516 Fixed
 #KT-4543 Fixed
 #KT-5291 Fixed
 #KT-5523 Fixed
 #KT-5582 Fixed

compiler/testData/codegen/box/objects/anonymousObjectPropertyInitialization.kt

@@ -0,0 +1,14 @@
+trait T {
+    fun foo(): String
+}
+
+val o = object : T {
+    val a = "OK"
+    val f = {
+        a
+    }()
+
+    override fun foo() = f
+}
+
+fun box() = o.foo()

compiler/testData/codegen/box/objects/localFunctionInObjectInitializer_kt4516.kt

@@ -0,0 +1,18 @@
+import java.util.HashMap
+
+object O {
+    val mmmap = HashMap<String, Int>();
+
+    {
+        fun doStuff() {
+            mmmap.put("two", 2)
+        }
+        doStuff()
+    }
+}
+
+fun box(): String {
+    val r = O.mmmap["two"]
+    if (r != 2) return "Fail: $r"
+    return "OK"
+}

compiler/testData/codegen/box/objects/objectInitialization_kt5523.kt

@@ -0,0 +1,6 @@
+object A {
+    val a = "OK"
+    val b = A.a
+}
+
+fun box() = A.b

compiler/testData/codegen/box/objects/objectVsClassInitialization_kt5291.kt

@@ -0,0 +1,24 @@
+public inline fun <T> T.with(f: T.() -> Unit): T {
+    this.f()
+    return this
+}
+
+public class Cls {
+    val string = "Cls"
+    val buffer = StringBuilder().with {
+        append(string)
+    }
+}
+
+public object Obj {
+    val string = "Obj"
+    val buffer = StringBuilder().with {
+        append(string)
+    }
+}
+
+fun box(): String {
+    if (Cls().buffer.toString() != "Cls") return "Fail class"
+    if (Obj.buffer.toString() != "Obj") return "Fail object"
+    return "OK"
+}

compiler/testData/codegen/box/objects/privateExtensionFromInitializer_kt4543.kt

@@ -0,0 +1,16 @@
+class A(val result: String)
+
+fun a(body: A.() -> String): String {
+    val r = A("OK")
+    return r.body()
+}
+
+object C {
+    private fun A.f() = result
+
+    val g = a {
+        f()
+    }
+}
+
+fun box() = C.g

compiler/testData/codegen/box/objects/privateFunctionFromClosureInInitializer_kt5582.kt

@@ -0,0 +1,20 @@
+trait T
+
+object Foo {
+    private fun foo(p: T) = p
+
+    private val v: Int = {
+        val x = foo(O)
+        42
+    }()
+
+    private object O : T
+
+    val result = v
+}
+
+fun box(): String {
+    val foo = Foo
+    if (foo.result != 42) return "Fail: ${foo.result}"
+    return "OK"
+}