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.
Enable the cors/ wpt subset

Fixes #3781
Remove unnecessary import of libgreen
auto merge of #3958 : zwarich/servo/remove-libgreen, r=Ms2ger
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.
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.
auto merge of #3951 : mrobinson/servo/iframes, r=jdm

This is the first step to allowing incremental iframe creation and destruction. This should eliminate task failures when an iframe is added to the frame tree lazily via script.