fixes dart.throw to work for non-objects

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 09f20c325aa4f867f2f56d2b43a885f9d92c3bbb..c320ca1d9817a5a01994305435634bd38408b5aa 100644
--- a/test/browser/runtime_tests.js
+++ b/test/browser/runtime_tests.js
@@ -23,6 +23,14 @@ suite('generic', () => {
     assert.throws(() => { generic(function(){}); });
   });
 
+  test('can throw number', () => {
+    try {
+      dart.throw(42);
+    } catch (e) {
+      assert.equal(e, 42);
+    }
+  });
+
   test('argument count cannot change', () => {
     let SomeType = generic(function(x) { return {x: x}; });
     assert.throws(() => { SomeType(1,2) });