Fix KT-1639: extend JFrame

#KT-1639 Fixed

compiler/testData/diagnostics/tests/regressions/kt1639-JFrame.jet

@@ -0,0 +1,9 @@
+package test
+
+import javax.swing.JFrame
+
+class KFrame() : JFrame() {
+    {
+        val x = this.accessibleContext // make sure field is visible
+    }
+}