[IR] Extend test coverage for smart cast handling.

compiler/testData/ir/irText/expressions/multipleSmartCasts.kt

@@ -0,0 +1,13 @@
+interface IC1 {
+    operator fun component1(): Int
+}
+
+interface IC2 {
+    operator fun component2(): String
+}
+
+fun test(x: Any) {
+    if (x is IC1 && x is IC2) {
+        val (x1, x2) = x
+    }
+}