The test injector now uses an XHR implementation based on DOM.getXHR,
which allows the current DOM adapter to dictate which XHR impl should
be used.
To prevent the changes to DOM adapter from introducing undesired new
dependencies into the benchmarks, separate the async facade into
a promise facade which is reexported by facade/async.
See #4539
BREAKING CHANGE:
This change moves the http module into angular2/, so its import
path is now angular2/http instead of http/http.
Many other modules have also been moved around inside of angular2,
but the public API paths have not changed as of this commit.
