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.
These wrappers are not natively understood by
ts2dart. Removing them will improve Dart2JS
compilation due to fewer megamorphic calls to List
functions.
It also makes Angular code more succinct and
improves type safety in Angular due to better type
inference of the Array component type.
This change exposed several bugs in Angular.