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

compiler/testData/diagnostics/tests/classObjects/ClassObjectCannotAccessClassFields.fir.kt

@@ -0,0 +1,9 @@
+// http://youtrack.jetbrains.net/issue/KT-20
+
+class A() {
+    val x = 1
+
+    companion object {
+        val y = <!UNRESOLVED_REFERENCE!>x<!>
+    }
+}