Autogenerate DOM bindings for Document.
auto merge of #627 : jdm/servo/docgen, r=kmc,jack
structural changes to support Iframes
handle pipeline exiting properly
navigation bug fix
switched window.page from *mut Page to @mut Page
removed a call to copy in servo.rc and renamed NavigationContext.navigate ==> NavigationContext.load
remove unused arg from script_task::handle_navigate_msg

remove unnecessary commented-out code
fix borrow check failures by reverting to storing *mut Page in window
updated rust-http-client submodule
auto merge of #628 : tkuehn/servo/master, r=metajack

Completed:
  * Replace pipeline navigation context with frame tree navigation context
  * Reuse script task for same origin iframes
  * Block on size future for iframe reflow
  * Remove global script context
  * Change codegen to use specific page context rather than script context.

Still to do:
  * Compositor's handling of relative frame positions
  * Compositor currently only asks for tiles from outermost frame
  * Window events are forwarded to the outermost frame's script. Should be routed to proper script via constellation.
  * Layout's sending of updated iframe sizes to constellation or size future (initial size only) as reflow is performed
constellation blocks on compositor before sending permission to paint to renderers
refactored for more code reuse in constellation
auto merge of #638 : tkuehn/servo/master, r=metajack

... renderers
FIXME: uint::range to vec`s iter().advance
auto merge of #640 : recrack/servo/fixme_each_mut, r=jdm
Replace some Option matching with higher order methods

This shrinks the code and should be easier to read if we are used to the
idioms.

Also change one copy to clone() while we're here.
Clean up calls to layout_root.dump()

We had two calls, one of which was dead code.
Derive Clone for FlowContext
Move is_root() into AbstractNode