Avoid marking codegen method bodies as unsafe twice
`CGAbstractMethod` takes a couple boolean parameters, among others:
* `extern`: will mark the method as `unsafe` and `extern`
* `unsafe`: will wrap the method body in an `unsafe` block
Passing both as `True` should not mark it as `unsafe` twice.
Example from a generated `HTMLCollectionBinding.rs`:
Before:
```
unsafe extern fn get_length(..) -> u8 {
unsafe {
// code here
}
}
```
After
```
unsafe extern fn get_length(..) -> u8 {
// code here
}
```
<!-- Reviewable:start -->
[<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/servo/7196)
<!-- Reviewable:end -->
`CGAbstractMethod` takes a couple boolean parameters, among others:
* `extern`: will mark the method as `unsafe` and `extern`
* `unsafe`: will wrap the method body in an `unsafe` block
Passing both as `True` should not mark it as `unsafe` twice.
Example from a generated `HTMLCollectionBinding.rs`:
Before:
```
unsafe extern fn get_length(..) -> u8 {
unsafe {
// code here
}
}
```
After
```
unsafe extern fn get_length(..) -> u8 {
// code here
}
```
Measure heap memory usage for more types. Fixes#6951
Also adds HeapSizeOf implementations/derive for some types. I've used "Cannot calculate Heap size" as a reason everywhere, because my imagination is rather limited. If you'd like me to change this message for specific types, please write something like this: "Trusted - Cannot calculate Heap size for Trusted" so that it would be easier for me to replace them through a script :)
<!-- Reviewable:start -->
[<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/servo/7097)
<!-- Reviewable:end -->
Implement getComputedStyle
It's not quite done but can probably be reviewed anyway.
I still need to finish up a few of the ToCss impls, I just got lazy and wanted to make sure things worked.
The computation of the used values is definitely not right, I'm going to investigate that.
<!-- Reviewable:start -->
[<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/servo/6798)
<!-- Reviewable:end -->
Introduce VirtualMethods::children_changed()
This virtual method mimics the behaviour of mutation observers and make it more viable than the older child_inserted(), which didn't cover removed nodes and was called as many times as there were inserted nodes.
A few other shortcomings where remove_child() was called directly instead of Node::remove() were also fixed while at it.
<!-- Reviewable:start -->
[<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/servo/6660)
<!-- Reviewable:end -->
To actually make the multiprocess communication work, we'll need to
reroute the task creation to the pipeline or the compositor. But this
works as a first step.
Fix a few issues
- Use SmallVec<[T; N]>
- Make find_iframe a free function
- Make ProgressEvent use enums for bubbles and cancelable
- Change README, as `rust-snapshot-hash` is just a text file
<!-- Reviewable:start -->
[<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/servo/6682)
<!-- Reviewable:end -->
