[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/tests/dataFlowInfoTraversal/MultiDeclaration.fir.kt

@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+
+operator fun Int.component1() = "a"
+
+fun foo(a: Number) {
+    val (x) = a as Int
+    checkSubtype<Int>(a)
+    checkSubtype<String>(x)
+}