Support for CSS Color Level 4 lab() and other modern color functions

Problem

html2canvas fails to parse modern CSS color functions introduced in CSS Color Level 4, specifically:

• lab() - CIELAB color space
• lch() - LCH color space
• oklab() - Oklab color space
• oklch() - Oklch color space

Error Message

Attempting to parse an unsupported color function "lab"

Example Code

.element {
  color: lab(50% 40 20);
  background: lch(60% 50 180);
}