De-@mut pipeline
Prevent '&nbsp' from stripping as whitespace
Fix: whitespace is considered as spaces(U+0020), tabs(U+0009), and line breaks(U+000D U+000A)
auto merge of #1728 : june0cho/servo/whitespace_nbsp, r=SimonSapin

Fix #1727.
auto merge of #1726 : pcwalton/servo/shut-down-profiler, r=kmcallister

This fixes a hang in content tests in my deleafset branch. No idea why it worked before though…

This just replicates the code in non-headless mode over to the headless mode.

r? @kmcallister
De-@mut the FrameTree.
Update rust-layers submodule
auto merge of #1712 : larsbergstrom/servo/more_atmuts, r=larsbergstrom,metajack

These commits remove @mut from the rest of Servo except for the script crate.

They rely on the hack `Rc` type exported from rust-layers, which will be removed once that same version lands in our Rust upgrade, but is required for now because otherwise I'd have to make all of these structures either `Send` or `Freeze`.

r? @metajack or @kmcallister
Remove commented-out parts of Document.webidl and HTMLDocument.webidl.
auto merge of #1729 : Ms2ger/servo/clear-document-idl, r=jdm

I don't see a good reason to keep those around for now
Create a Line DisplayItem
auto merge of #1709 : sankha93/servo/issue221, r=larsbergstrom

This fixes #221.

I used the `BaseDisplayItem` class to define rectangle in which the line will be drawn. The width of the rectangle will be used as the thickness of the line segment.
Fix #922: Bindings generator generates .pyc files
auto merge of #1735 : tgkokk/servo/python-write-bytecode, r=kmcallister

Forgot to actually claim #922. I hope no one is working on it.

I removed `PYTHONDONTWRITEBYTECODE=1` from every relevant file and I added code for removing `*.pyc` files in `clean-script` in `mk/clean.mk`. You might want to move the main logic into a function like `REMOVE_PYC_FILES`, since the files will exist eventually in other trees under `/src`. I used `find` in order to find all `*.pyc` files, since they might be in other subdirectories.

This is my first PR, so feel free to give me any feedback you might think is necessary.
Implement JSManaged for DOM objects.
auto merge of #1591 : jdm/servo/jsmanaged, r=Ms2ger
Initial unmodified dump of Gecko's union codegen.
Implement WebIDL union support.
Clean up TrySetTo interface to avoid mutable outrefs.
Remove commented bits that aren't necessary.