Closes GH-671.

Closes GH-674.

Improvements:
* Removes an unnecessary variable
* Avoids having two variables with the same name
* Avoids re-declaring an existing parameter
* Removes an unnecessary ternary operator
* Avoid an inline short-circuit expression for greater clarity.

The fact that the mode parameter is optional for fs.open and
fs.openSync was not documented.

Problem: Omitting the mode parameter causes the provided callback
parameter to never fire. This was originally fixed in 6078c37b and
later broken in 5f2e9093.

Solution: Overwriting the value of a parameter also overwrites the
reference in the arguments object. This patch works arround this
fact by not touching the mode parameter until a reference to the
callback has been established.

Should re-enable crankshaft; can build w/ snapshot again.

thanks Toshihiro

Closes GH-653.

This is important so that in the future, this will work:

    $ cd ~/dev/js/some-project
    $ npm install redis
    $ node
    > require.resolve('redis')
    '/Users/isaacs/dev/js/some-project/node_modules/redis/index.js'

This works for both ServerResponse and ClientRequest.
Adds three new methods as a couple properties to to OutgoingMessage objects.
Tests by Charlie Robbins.

Change-Id: Ib6f3829798e8f11dd2b6136e61df254f1564807e

Needs more tests.

Thanks Sitelier. Closes GH-651.

See http://code.google.com/p/v8/issues/detail?id=884