fixes #175, fixed arrays

test/browser/runtime_tests.js

Index: test/browser/runtime_tests.js
diff --git a/test/browser/runtime_tests.js b/test/browser/runtime_tests.js
index 824edd574a3d34441a0f98d100302ae3cd195ee0..9b84c9bc6b5800df8536100a5c66fd9c3e6a9b1e 100644
--- a/test/browser/runtime_tests.js
+++ b/test/browser/runtime_tests.js
@@ -391,3 +391,13 @@ suite('instanceOf', () => {
     assert.equal(intType, core.int);
   });
 });
+
+suite('primitives', function() {
+  'use strict';
+
+  test('fixed length list', () => {
+    let list = new core.List(10);
+    list[0] = 42;
+    assert.throws(() => list.add(42));
+  });
+});