Close #84

Actually <img> elements in <noscript> are not prefetched anymore.

Probably because html5ever already parses the <noscript> content as raw
text data if `scripting_enabled` is activated.

See
https://github.com/servo/html5ever/blob/servo/src/tree_builder/rules.rs#
L126

Also, added a test to the images cache.
embedding: begin cef string_map api

cef_string_map_alloc()
embedding: cef_string_map_size()
embedding: cef_string_map_append()
embedding: cef_string_map_find()
embedding: cef_string_map_key()
embedding: cef_string_map_value()
embedding: cef_string_map_clear()
embedding: cef_string_map_free()
embedding: rename string_list internal function to string_list instead of string_map
embedding: cef_string_utf8_cmp()
Enable the cors/ wpt subset

Fixes #3781
Change /cors/remote-origin.htm.ini to CRASH
auto merge of #3952 : andrewguertin/servo/wpt-cors, r=Manishearth

Fixes #3781 

I had to make a small fix to wptrunner's wptupdate, but otherwise the instructions at https://github.com/servo/servo/blob/master/tests/wpt/README.md#updating-test-expectations were good and this was very straightforward.
Clip display list based on frame viewport

Instead of creating a display list for the entire page, only create one
for an area that expands around the viewport. On my machine this makes
incremental layout of http://timecube.com 50% faster.
auto merge of #3934 : guillaumebort/servo/fix/84, r=jdm

Actually `<img>` elements in `<noscript>` are not prefetched anymore.

Probably because html5ever already parses the `<noscript>` content as raw
text data if `scripting_enabled` is activated.

See https://github.com/servo/html5ever/blob/servo/src/tree_builder/rules.rs#L126

Also, added a test to the images cache.
Rename LoadIframeUrlMsg to CreateIFrameAndLoadUrlMsg

This better reflects what the message does.
Small fix to variable name

This is a more accurate name for the script pipeline.
Add some factory methods for frame tree types
Send incremental frame tree updates to the compositor

This allows the compositor to add frames after the call to SetIds,
where the initial frame tree is created. There are still some issues
preventing proper late frame creation, but this prevents crashes when
it happens.

Fixes #3738.