[Telemetry] Validate args in js_template rendering

telemetry/telemetry/util/js_template_unittest.py

Index: telemetry/telemetry/util/js_template_unittest.py
diff --git a/telemetry/telemetry/util/js_template_unittest.py b/telemetry/telemetry/util/js_template_unittest.py
index ac0b3a5a419e26afdc2ad9af01507b388bbe416d..c3d698aef975bfcb585b513f3ce6a14e759be19c 100644
--- a/telemetry/telemetry/util/js_template_unittest.py
+++ b/telemetry/telemetry/util/js_template_unittest.py
@@ -40,3 +40,7 @@ class JavaScriptTemplateTest(unittest.TestCase):
   def testRenderRaisesWithBadLiteralValue(self):
     with self.assertRaises(ValueError):
       js_template.Render('function() { {{ @code }} }', code=['foo', 'bar'])
+
+  def testRenderRaisesWithUnusedKeywordArgs(self):
+    with self.assertRaises(TypeError):
+      js_template.Render('foo = {{ x }};', x=4, y=5, timemout=6)