Deduped modules don't get included in worker blob

This causes an exception at runtime when the missing module is required.

The `resolveSources` function tries to recursively find all dependencies, but it doesn't know about modules that are deduped, which have an entry in the modules map that looks like this:

```js
"/Users/jhiesey/Projects/node/stream-http/node_modules/inherits/inherits_browser.js": [function(require, module, exports) {
arguments[4]["/Users/jhiesey/Projects/node/airtap/node_modules/inherits/inherits_browser.js"][0].apply(exports, arguments)
}
, {}]
```

The module the dedupe entry points to ("/Users/jhiesey/Projects/node/airtap/node_modules/inherits/inherits_browser.js") needs to be included too, but `resovleSources` doesn't know that, so the dedupe entry throws at runtime.

Start by locating the resolveSources function and tracing how it walks the modules map, then inspect the dedupe entry and its target module path. Reproduce the worker runtime exception with a deduped dependency; done means the referenced module is included in the worker blob and requiring it succeeds.

Written by the indexing model from the issue text.