KT-5455 Need warning about redundant type cast

#KT-5455 Fixed

compiler/testData/diagnostics/tests/smartCasts/kt5455.kt

@@ -0,0 +1,28 @@
+//KT-5455 Need warning about redundant type cast
+fun foo(o: Any): Int {
+    if (o is String) {
+        return (o <!USELESS_CAST_STATIC_ASSERT_IS_FINE!>as<!> String).length
+    }
+    return -1
+}
+
+open class A {
+    fun foo() {}
+}
+class B: A()
+
+fun test(a: Any?) {
+    if (a is B) {
+        (a <!USELESS_CAST_STATIC_ASSERT_IS_FINE!>as<!> A).foo()
+    }
+}
+
+fun test1(a: B) {
+    (a <!USELESS_CAST_STATIC_ASSERT_IS_FINE!>as<!> A?)?.foo()
+}
+
+fun test2(b: B?) {
+    if (b != null) {
+        (b <!USELESS_CAST_STATIC_ASSERT_IS_FINE!>as<!> A).foo()
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/kt5455.txt

@@ -0,0 +1,22 @@
+package
+
+internal fun foo(/*0*/ o: kotlin.Any): kotlin.Int
+internal fun test(/*0*/ a: kotlin.Any?): kotlin.Unit
+internal fun test1(/*0*/ a: B): kotlin.Unit
+internal fun test2(/*0*/ b: B?): kotlin.Unit
+
+internal open class A {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    internal final fun foo(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+internal final class B : A {
+    public constructor B()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    internal final override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}