Code review comments

lib/debug/asserts.js

@@ -49,6 +49,7 @@ shaka.asserts.patchAssert_ = function() {
   if (!assert) {
     console.assert = function() {};
   } else if (!assert.bind) {
+    // IE 9 does not provide a .bind for the built-in console functions.
     console.assert = function() {
       assert.apply(console, arguments);
     }