Drop traits with required classes

#KT-4771 Rejected

compiler/testData/codegen/box/bridges/complexMultiInheritance.kt

@@ -2,8 +2,6 @@ open class A {
     open fun foo(): Any = "A"
 }
 
-interface B : A
-
 open class C : A() {
     override fun foo(): Int = 222
 }
@@ -12,14 +10,13 @@ interface D {
     fun foo(): Number
 }
 
-class E : B, C(), D
+class E : C(), D
 
 fun box(): String {
     val e = E()
     if (e.foo() != 222) return "Fail 1"
     if ((e : D).foo() != 222) return "Fail 2"
     if ((e : C).foo() != 222) return "Fail 3"
-    if ((e : B).foo() != 222) return "Fail 4"
-    if ((e : A).foo() != 222) return "Fail 5"
+    if ((e : A).foo() != 222) return "Fail 4"
     return "OK"
 }

compiler/testData/codegen/box/bridges/fakeOverrideInTraitWithRequiredFromTraitImpl.kt

@@ -1,17 +0,0 @@
-abstract class A {
-    abstract fun foo(): Any
-}
-
-interface B {
-    fun foo(): String = "B"
-}
-
-interface C : A, B
-
-class D : A(), C
-
-fun box(): String {
-    val d = D()
-    val r = d.foo() + (d : C).foo() + (d : B).foo() + (d : A).foo()
-    return if (r == "BBBB") "OK" else "Fail: $r"
-}

compiler/testData/codegen/box/bridges/traitWithRequiredCovariantOverride.kt

@@ -1,15 +0,0 @@
-open class A {
-    open fun foo(): Any = "A"
-}
-
-interface B : A {
-    override fun foo(): String = "B"
-}
-
-class C : A(), B
-
-fun box(): String {
-    val c = C()
-    val r = c.foo() + (c : B).foo() + (c : A).foo()
-    return if (r == "BBB") "OK" else "Fail: $r"
-}