Minor, delete Object from some test data

compiler/testData/codegen/box/functions/defaultargs.kt

@@ -1,4 +1,4 @@
-open abstract class B() : java.lang.Object() {
+open abstract class B {
     fun foo(arg: Int = 239 + 1) : Int = arg
 }
 

compiler/testData/codegen/box/functions/defaultargs1.kt

@@ -1,4 +1,4 @@
-fun <T> T.toPrefixedString(prefix: String = "", suffix: String="") = prefix + (this as java.lang.Object).toString() + suffix
+fun <T> T.toPrefixedString(prefix: String = "", suffix: String="") = prefix + this.toString() + suffix
 
 fun box() : String {
     if("mama".toPrefixedString(suffix="321", prefix="papa") != "papamama321") return "fail"

compiler/testData/codegen/box/functions/defaultargs4.kt

@@ -4,12 +4,11 @@ trait A {
     fun bar(arg: Int = 240) : Int = bar2(arg/2)
 }
 
-open abstract class B() : A, java.lang.Object() {
+open abstract class B : A {
     override fun bar2(arg: Int) : Int = arg
 }
 
-class C() : B() {
-}
+class C : B()
 
 fun box() : String {
     if(C().bar(10) != 5) return "fail"

compiler/testData/codegen/box/functions/defaultargs5.kt

@@ -1,8 +1,8 @@
-open abstract class B() : java.lang.Object() {
+open abstract class B {
     abstract fun foo2(arg: Int = 239) : Int
 }
 
-class C() : B() {
+class C : B() {
     override fun foo2(arg: Int) : Int = arg
 }