FIR2IR: fix smart casts in case field is accessed

compiler/testData/ir/irText/firProblems/JCTree.kt

@@ -0,0 +1,24 @@
+// FILE: JCTree.java
+
+public class JCTree {
+    public abstract static class JCExpression extends JCTree {
+
+    }
+
+    public static class JCTypeApply extends JCExpression {
+        public String clazz = "OK";
+    }
+}
+
+// FILE: JCTreeUser.kt
+
+class Owner<out T : JCTree>(val tree: T) {
+    val foo: String
+        get() {
+            var tree: JCTree = tree
+            if (tree is JCTree.JCTypeApply) {
+                return tree.clazz
+            }
+            return "";
+        }
+}