Once issue 6943 is fixed, the http package will start using pub's
cross-platform library support to work with both dart:io and
dart:html. However, this package is also used *within* pub, so we need
a way for pub to import it that doesn't require it being run through
pub.
This change supports this by stripping out and dart:html imports from
the http package and creating a special packages directory only used
by pub that uses this modified version.
BUG=20068
R=floitsch@google.com
Review URL: https://codereview.chromium.org//397773002
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@38255 260f80e4-7a28-3924-810f-c04153c831b5
nweiz@google.com
d8663eeeda