Add chrome.extension to extension_api.json and docs

Add chrome.extension to extension_api.json and docs.

This required making it so that extension_api.json definitions defer to existing bindings so that the chrome.extension object can remain setup in renderer_extension_bindings.js.

Also fixed a minor bug with error handling in the api_generator.js

Moved "Port" type to the new extension module.

Removed a bunch of trailing whitespace from the extension_api.json.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=23200

[Aaron Boodman, 2009-08-11 21:54:53]

lgtm.

the comment in connect() is not correct per our discussion offline.