Support web worker usage.

See lodash/lodash#458.
Assign `freeGlobal` correctly in `node-webkit`.

See lodash/lodash#419.

Remove the now-unused `isHostType` function.
Avoid setting `freeGlobal` to Rhino's `global()`.
Update browser benchmark harness
Add the `tar` module to `vendor`.
Remove the Closure Compiler from `vendor`.
`build.js`: Lazily download the Closure Compiler.

The `getCompiler()` helper attempts to download the latest version of
the Compiler from Google's servers, stores the `ETag` of the requested
bundle in `vendor/closure-compiler-etag.txt`, and extracts the `.jar`
from the bundle into `vendor/closure-compiler.jar`.

The cached `ETag` is presented in the `If-None-Match` header for all
subsequent requests, ensuring that the Compiler is only re-downloaded
when a new version is available. If the latest version cannot be
downloaded, the builder will use a previously-downloaded copy.

Addresses #54.
`build.js`: Fix `getCompiler()` for offline use.

`getCompiler()` should not wait for `saveETag()` if a connection
error occurs and the `response` event is never fired.
Syncing up with `gh-pages`.
Ensure that `tar`'s dependencies are checked in.
Test `dev` branch on Travis
Update Douglas Crockford's JSON implementations [ci skip]
`noConflict()`: Restore `JSON` and `JSON3`.

`noConflict()` no longer restores the global `JSON` and `JSON3`
objects to their original values when invoked multiple times.

Closes #56.
JSON v3.3.1.