Low-latency rendering with the desynchronized hint

[wdanilo]

Pull Request Description

This PR adds desynchronized hint to the WebGL context which invokes a different code path that bypasses the usual DOM update mechanism. To learn more, see: https://developer.chrome.com/blog/desynchronized/

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• Screenshots/screencasts have been attached, if there are any visual changes. For interactive or animated visual changes, a screencast is preferred.
• All code follows the
  Scala,
  Java,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• All code has been tested:
  • Unit tests have been written where possible.
  • If GUI codebase was changed, the GUI was tested when built using ./run ide build.

[wdanilo]

I did self-QA end everything seems to work.

[farmaazon]

I read the link, and I'm a bit unsure about it.

First, it does not explain directly what are drawbacks of setting this option. I guess there are some, as otherwise this would be default in every browser. We display both canvas as other HTML elements, so we may technically be affected.

Furthermore, I don't know why we do not add "preserveDrawingBuffer" option as described in https://developer.chrome.com/blog/desynchronized/#avoiding-flicker

Moreover, there is a warning in https://developer.chrome.com/blog/desynchronized/#alpha-channels that:

A translucent canvas element, one where alpha is set to true, can still be desynchronized, but it must not have any other DOM elements above it.

But we definitely have other DOM elements above our canvas, and it definitely has alpha.

I think these things should be discussed in the comment. Otherwise anyone else who will read the article may ask same questions.

[wdanilo]

We will not enable it for now. Why not is described here and here, and a good summary is here: