Introduction of CastedClassReceiver and its handling in codegen #KT-6744 Fixed

ClassReceiver converted to Kotlin
Also #KT-7617 Fixed

compiler/testData/codegen/box/smartCasts/falseSmartCast.kt

@@ -0,0 +1,17 @@
+open class SuperFoo {
+    public fun bar(): String {
+        if (this is Foo) {
+            superFoo() // Smart cast
+            return baz() // Cannot be cast
+        }
+        return baz()
+    }
+
+    public fun baz() = "OK"
+}
+
+class Foo : SuperFoo() {
+    public fun superFoo() {}
+}
+
+fun box(): String = Foo().bar()

compiler/testData/codegen/box/smartCasts/implicitExtensionReceiver.kt

@@ -0,0 +1,7 @@
+class A {
+    fun foo() = "OK"
+}
+
+fun A?.bar() = if (this != null) foo() else "FAIL"
+
+fun box() = A().bar()

compiler/testData/codegen/box/smartCasts/implicitMemberReceiver.kt

@@ -0,0 +1,20 @@
+open class A {
+    open val a = "OK"
+}
+
+class B : A() {
+    override val a = "FAIL"
+    fun foo() = "CRUSH"
+}
+
+class C {
+    fun A?.complex(): String {
+        if (this is B) return foo()
+        else if (this != null) return a
+        else return "???"
+    }
+
+    fun bar() = A().complex()
+}
+
+fun box() = C().bar()

compiler/testData/codegen/box/smartCasts/implicitReceiver.kt

@@ -0,0 +1,13 @@
+open class A {
+    class B : A() {
+        val a = "FAIL"
+    }
+
+    fun foo(): String {
+        if (this is B) return a
+        return "OK"
+    }
+}
+
+
+fun box(): String = A().foo()

compiler/testData/codegen/box/smartCasts/implicitReceiverInWhen.kt

@@ -0,0 +1,11 @@
+open class A {
+    fun f(): String =
+            when (this) {
+                is B -> x
+                else -> "FAIL"
+            }
+}
+
+class B(val x: String) : A()
+
+fun box() = B("OK").f()

compiler/testData/codegen/box/smartCasts/implicitToGrandSon.kt

@@ -0,0 +1,13 @@
+open class A {
+    open fun foo() = "FAIL"
+
+    fun bar() = if (this is C) foo() else foo()
+}
+
+open class B : A()
+
+open class C : B() {
+    override fun foo() = "OK"
+}
+
+fun box() = C().bar()