Disable the phantom QPA on Windows.

It cannot, nor should it, be selected on windows machines. There, we
stick to the Windows QPA which is required to get a lot of things up
and running, like an eventloop, socket integration etc. pp.

There was code in the phantom QPA to make it compile, but it never
actually worked since a lot of things where missing (such as
instantiating QWindowsContext among others).

https://github.com/ariya/phantomjs/issues/12494
Fix OS X stdout, stdin, and stderr.

To prevent unintended macro expansion, don't use the name
stdout/stdin/stderr in the native System object. Those properties are
achieved by shadowing it in the module interface (JavaScript side).

https://github.com/ariya/phantomjs/issues/12496
Remove GIF format for screen capture export (render).

This is to reduce maintenance burden.  A GIF representation of a web
page can be produced by converting its PNG capture. There are numerous
third-party tools which can do the job better (optimized palette,
minimized loss, etc).

https://github.com/ariya/phantomjs/issues/12480
Enable more system module tests.

https://github.com/ariya/phantomjs/issues/12496
Reenable some more tests.

Now that the failing tests are isolated (among other, PDF crashing of
https://github.com/ariya/phantomjs/issues/12500), more tests should be
enabled. Going from 270 specs to 316 specs.

https://github.com/ariya/phantomjs/issues/10448
Enable even more tests (to 322 specs).

https://github.com/ariya/phantomjs/issues/10448
A revamped test runner.

This Python script serves as a master test runner. It will run each test
script with a fresh instance of PhantomJS. The exit code of each script
determines its success or failure.

The existing tests (run-tests.js) are wrapped as one of the test
scripts. This permits a gradual migration to the new test system.

https://github.com/ariya/phantomjs/issues/12439