boxy-svg.com - site is not usable

[karlcow]

URL: https://boxy-svg.com/app

Browser / Version: Firefox 94.0
Operating System: Mac OS X 10.15
Tested Another Browser: Yes Edge

Problem type: Site is not usable
Description: Browser unsupported
Steps to Reproduce:

1. Go to https://boxy-svg.com/app

Expected:
Use the SVG editor

Actual:
Redirected to https://boxy-svg.com/requirements

This happens in https://boxy-svg.com/runtime/web-preload.js

which contains

(function() {
  var isSupportedBrowser = (
    window.customElements                        !== undefined &&
    window.customElements.define                 !== undefined &&
    window.requestIdleCallback                   !== undefined &&
    window.Animation                             !== undefined &&
    window.CSSStyleSheet                         !== undefined &&
    window.CSSStyleSheet.prototype.replaceSync   !== undefined &&
    window.DOMPoint                              !== undefined &&
    window.DOMRect                               !== undefined &&
    window.HTMLDialogElement                     !== undefined &&
    window.HTMLDialogElement.prototype.showModal !== undefined &&
    window.MutationObserver                      !== undefined &&
    window.PointerEvent                          !== undefined &&
    window.ResizeObserver                        !== undefined &&
    window.ShadowRoot                            !== undefined &&
    window.CSS                                   !== undefined &&
    window.CSS.supports("color", "var(--test)")                &&
    window.CSS.supports("d", "path('M 0 0 H 10')")
  );

  if (isSupportedBrowser === false) {
    window.location.replace("/requirements");
  }
  else {
…
}

The part which fails is

window.CSSStyleSheet.prototype.replaceSync which is behind a pref in about:config on Firefox Nightly 94.

This fails too in Safari Tech Preview, which has no support at all.
For Firefox https://bugzilla.mozilla.org/show_bug.cgi?id=1613746

View the screenshot

Browser Configuration

• gfx.webrender.all: false
• gfx.webrender.blob-images: true
• gfx.webrender.enabled: false
• image.mem.shared: true
• buildID: 20210930095024
• channel: nightly
• hasTouchScreen: false
• mixed active content blocked: false
• mixed passive content blocked: false
• tracking content blocked: false

View console log messages

From webcompat.com with ❤️

[karlcow]

Close as duplicate of https://bugzilla.mozilla.org/show_bug.cgi?id=1613746

[karlcow]

In fact it's more https://bugzilla.mozilla.org/show_bug.cgi?id=1644101

[karlcow]

I didn't find a webkit bug for it.
so I opened one.
https://bugs.webkit.org/show_bug.cgi?id=231054

[karlcow]

for Safari it will be a bit harder to solve. These are all missing.

window.requestIdleCallback
window.CSSStyleSheet.prototype.replaceSync
window.HTMLDialogElement                    
window.HTMLDialogElement.prototype.showModal
window.CSS.supports("d", "path('M 0 0 H 10')")

[karlcow]

For Safari

• https://bugs.webkit.org/show_bug.cgi?id=164193
• https://bugs.webkit.org/show_bug.cgi?id=84635
• pretty sure there must be a d path bug