Do not unbox nullable Result, since before usage it is coerced

#KT-46505

compiler/testData/codegen/box/inlineClasses/unboxGenericParameter/objectLiteral/nullableResult.kt

@@ -0,0 +1,24 @@
+// !LANGUAGE: +InlineClasses
+// WITH_RUNTIME
+// IGNORE_BACKEND: JVM
+// IGNORE_LIGHT_ANALYSIS
+
+fun <T> foo(a: Result<T>?): T? = bar(a, object : IFace<Result<T>, T> {
+    override fun call(ic: Result<T>?): T? = ic?.getOrThrow()
+})
+
+interface IFace<T, R> {
+    fun call(ic: T?): R?
+}
+
+fun <T, R> bar(value: T?, f: IFace<T, R>): R? {
+    return f.call(value)
+}
+
+fun box(): String {
+    var res = foo<Int>(Result.success(40))?.plus(2)
+    if (res != 42) return "FAIL $res"
+    res = foo<Int>(null)
+    if (res != null) return "FAIL $res"
+    return "OK"
+}