Fixes wait2/waitAll implementations in the Promises blog post.

_posts/2015-11-15-how-do-promises-work.md

@@ -925,8 +925,7 @@ function wait2(promiseA, promiseB, expression) {
With this, we can define `circleAreaPromise` as the following:

{% highlight js linenos=table %}
var circleAreaPromise = chain(wait2(radiusPromise, piPromise),
                              circleAreaAbstraction);
var circleAreaPromise = wait2(radiusPromise, piPromise, circleAreaAbstraction);
{% endhighlight %}

We could define `wait3` for expressions that depend on three values,
@@ -945,7 +944,7 @@ State Machine, but there is no implicit ordering (besides JavaScript's
own execution semantics).

{% highlight js linenos=table %}
function waitAll(promises, expression) {
function waitAll(promises) {
  // An array of the values of the promise, which we'll fill in
  // incrementally.
  var values = new Array(promises.length);