add testcase for mozilla#575 that proofs this already works

Author: rbri

tests/src/test/java/org/mozilla/javascript/tests/es6/InstanceofTest.java

@@ -0,0 +1,22 @@
+package org.mozilla.javascript.tests.es6;
+
+import org.junit.Test;
+import org.mozilla.javascript.testutils.Utils;
+
+/** Test for instanceof operator. */
+public class InstanceofTest {
+
+    @Test
+    public void rightHandSideNotCallable() {
+        String js =
+                "try {\n"
+                        + "  throw SyntaxError();\n"
+                        + "} catch (e) {\n"
+                        + "  var value = (e instanceof SyntaxError());\n"
+                        + "}";
+
+        Utils.assertEcmaError(
+                "TypeError: Target of ``instanceof`` must be callable or have ``[Symbol.hasInstance]`` method.",
+                js);
+    }
+}