add `npm run profile`.

* This should open up a new window (ideally Chrome).
* Pop open the Dev Tools. Click on the Profile tab.
* Hit escape to view the console as well.
* Once the profile "all" is complete, you should be able to inspect the run.

Of note: V8 has a sampling profiler -- so if the stacks look a bit odd, it's usually
because the sampling caught at a weird moment. By default the benchmark is configured
to run each of:

1. Large: Unminified, concatenated JSHint codebase.
2. Medium: Unminified, concatenated jQuery 2.1.0 codebase.
3. Small: Unminified, concatenated Knockout codebase.

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The Chrome dev tools are pretty awesome for inspecting where your JS is spending the most time:

It can show you what functions are called the most / take the most time out of a run & reasons they haven't been optimized:

![heavy view](https://f.cloud.github.com/assets/37303/2095270/0bcd55fa-8ee0-11e3-8550-b2a211e6b1f6.png)

As well as a flamegraph:

![flamegraph](https://f.cloud.github.com/assets/37303/2095273/3135081a-8ee0-11e3-9b42-60e8a4f056d4.png?bustcache)