* Simpler image cache API for clients to use.
* Significantly fewer threads.
* One thread for image cache task (multiplexes commands, decoder threads and async resource requests).
* 4 threads for decoder worker tasks.
* Removed ReflowEvent hacks in script and layout tasks.
* Image elements pass a Trusted<T> to image cache, which is used to dirty nodes via script task. Previous use of Untrusted addresses was unsafe.
* Image requests such as background-image on layout / paint threads trigger repaint only rather than full reflow.
* Add reflow batching for when multiple images load quickly.
* Reduces the number of paints loading wikipedia from ~95 to ~35.
* Reasonably simple to add proper prefetch support in a follow up PR.
* Async loaded images always construct Image fragments now, instead of generic.
* Image fragments support the image not being present.
* Simpler implementation of synchronous image loading for reftests.
* Removed image holder.
* image.onload support.
* image NaturalWidth and NaturalHeight support.
* Updated WPT expectations.
"Links to the multipage version of the specification are unfortunately
likely to break over time."
-- https://html.spec.whatwg.org/multipage/asefij.html
This commit removes all references to the specific pages when viewing
WHATWG using multipage mode. I went through all these links and they
redirect fine.
Regex used to generate this commit:
`s_whatwg.org/multipage/.*#_whatwg.org/multipage/#_g`
Extracted this out of #5649
This commit was created with the following commands:
```
find . -iname "*.webidl" -type f -print0 | xargs -0 sed -i '' 's/http:\(.*\)whatwg.org/https:\1whatwg.org/g'
```
```
find . -iname "*.rs" -type f -print0 | xargs -0 sed -i '' 's/http:\(.*\)whatwg.org/https:\1whatwg.org/g'
```
This exposes some other canvas tests which were marked as PASS before. Two strokeRect related tests are fixed by #5612, and lineCap/lineJoin will have an implementation soon.
The first commit refactors the fragment parsing and innerHTML setter. This makes the code mirror the structure of the spec more closely, and also prepares for reusing code with the outerHTML setter.
