[IR] Extend test coverage for smart cast handling.

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

@@ -0,0 +1,22 @@
+interface IC1 {
+    operator fun component1(): String
+}
+
+interface IC2 {
+    operator fun component2(): String
+}
+
+class A : IC1, IC2 {
+    override fun component1(): String = "O"
+    override fun component2(): String = "K"
+}
+
+fun test(x: Any): String {
+    if (x is IC1 && x is IC2) {
+        val (x1, x2) = x
+        return "$x1$x2"
+    }
+    return "FAIL"
+}
+
+fun box(): String = test(A())