Implement Location.search.
Make some DOM members private.

I have not reviewed if this is the complete set of members that can be made
private.
Remove deref_mut from Untraceable/Traceable (fixes #2736)
Font refactoring - remove unstyled method, update android freetype
init to use allocator hooks.
Add URLSearchParams interface with serialization support
Filter response headers
Fix wpt failure on responseType setter
Update test expectations for #2731
Merge pull request #2728 from Ms2ger/location-search

Implement Location.search.
Refactor compositor layer tree design

Instead of having two parallel trees of CompositorLayers and
ContainerLayers, transform CompositorLayer to CompositorData and move
tiling logic to rust-layers.
Merge pull request #2727 from Ms2ger/dom-pub

Make some DOM members private.
Update to latest servo-android-glue
Merge pull request #2749 from mbrubeck/glue-submodule

Update to latest servo-android-glue
Merge pull request #2745 from glennw/remove-unstyled-method

Font refactoring - remove unstyled method, update android freetype
Merge pull request #2737 from Manishearth/derefmut-2736

Remove deref_mut from Untraceable/Traceable (fixes #2736)
Merge pull request #2735 from Manishearth/urlsearchparams

Add URLSearchParams interface with serialization support
Merge pull request #2731 from Manishearth/xhr-wpt-header-filter

Filter response headers, fix responseType's error in XHR
First part of font refactoring. These changes simplify a few things
but don't do much on their own, they just make it easier to
implement the work to come (web fonts, performance improvments
in terms of font loading and memory usage).

- Font identifier on Linux/Android is now the font file path.
  This is a temporary measure, but simplifies things a lot for now.
- Remove FontListHandleMethods trait in favour of free functions.
- FontList::refresh() has no knowledge of FontFamily etc. Instead it takes
  a closure that the caller provides.
- FontList::load_variations_for_family no longer creates the font
  handle. Instead it takes a closure and provides the name of the font
  identifier for the variations it finds.
- Remove path_from_identifier() - it's no longer required.
- create_font_from_identifier() takes an Option<Style>, allowing it to be
  used to create fonts for family matching purposes where the font size is
  not important.

Tested on Linux + Mac. Builds on Android but not able to confirm it's working correctly.
Merge pull request #2748 from mrobinson/layer-reorg

Refactor compositor layer tree design
Fetch Rust snapshots over HTTPS. Fix #2752