The HTTP headers object in request and response objects is now marked
as non-mutable when it cannot be changed. An exception will be thrown
if trying to mutate headers when they are not mutable.
Postponed the sending of the headers until either the first byte of
body data is sent or the empty body is indicated. This is to allow
getting the output stream object and still be able to set headers
until the actual body is touched.
Added checking of the number of bytes of body data transmitted when an
explicit content length is specified.
R=ajohnsen@google.com
BUG=none
TEST=tests/standalone/src/io/HttpHeadersState.dart,tests/standalone/src/io/HttpContentLengthTest.dart
Review URL: https://chromiumcodereview.appspot.com//10232006
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@7010 260f80e4-7a28-3924-810f-c04153c831b5
sgjesse@google.com
ebc838c963