6.0.0

• Significant changes to the supported list of CSS properties to match the latest CSS specifications:
  • Many new ones are added, with generic processing.
  • The following are added with special processing: border-block-end-color, border-block-start-color, border-inline-end-color, border-inline-start-color, text-emphasis-color.
  • The following nonstandard properties are deleted: -webkit-background-composite, -webkit-border-after, -webkit-border-after-color, -webkit-border-after-style, -webkit-border-after-width, -webkit-border-before, -webkit-border-before-color, -webkit-border-before-style, -webkit-border-before-width, -webkit-border-end, -webkit-border-end-color, -webkit-border-end-style, -webkit-border-end-width, -webkit-border-fit, -webkit-border-horizontal-spacing, -webkit-border-start, -webkit-border-start-color, -webkit-border-start-style, -webkit-border-start-width, -webkit-border-vertical-spacing, -webkit-color-correction, -webkit-column-axis, -webkit-column-break-after, -webkit-column-break-before, -webkit-column-break-inside, -webkit-column-rule-color, -webkit-flex-align, -webkit-flex-item-align, -webkit-flex-line-pack, -webkit-flex-order, -webkit-flex-pack, -webkit-font-size-delta, -webkit-font-smoothing, -webkit-highlight, -webkit-hyphenate-limit-after, -webkit-hyphenate-limit-before, -webkit-locale, -webkit-logical-height, -webkit-logical-width, -webkit-margin-after, -webkit-margin-after-collapse, -webkit-margin-before, -webkit-margin-before-collapse, -webkit-margin-bottom-collapse, -webkit-margin-collapse, -webkit-margin-end, -webkit-margin-start, -webkit-margin-top-collapse, -webkit-marquee, -webkit-marquee-direction, -webkit-marquee-increment, -webkit-marquee-repetition, -webkit-marquee-speed, -webkit-marquee-style, -webkit-mask-attachment, -webkit-mask-position-x, -webkit-mask-position-y, -webkit-mask-repeat-x, -webkit-mask-repeat-y, -webkit-match-nearest-mail-blockquote-color, -webkit-max-logical-height, -webkit-max-logical-width, -webkit-min-logical-height, -webkit-min-logical-width, -webkit-nbsp-mode, -webkit-overflow-scrolling, -webkit-padding-after, -webkit-padding-before, -webkit-padding-end, -webkit-padding-start, -webkit-perspective-origin-x, -webkit-perspective-origin-y, -webkit-region-break-after, -webkit-region-break-before, -webkit-region-break-inside, -webkit-region-overflow, -webkit-rtl-ordering, -webkit-svg-shadow, -webkit-tap-highlight-color, -webkit-text-decorations-in-effect, -webkit-text-emphasis-color, -webkit-text-security, -webkit-transform-origin-x, -webkit-transform-origin-y, -webkit-transform-origin-z, -webkit-user-drag, -webkit-user-modify, -webkit-wrap, -webkit-wrap-margin, -webkit-wrap-padding, -webkit-wrap-shape-inside, -webkit-wrap-shape-outside, -webkit-zoom, color-profile, color-rendering, enable-background, glyph-orientation-horizontal, kerning, marker-offset, marks, size, src, text-line-through, text-line-through-color, text-line-through-mode, text-line-through-style, text-line-through-width, text-overline, text-overline-color, text-overline-mode, text-overline-style, text-overline-width, text-underline, text-underline-color, text-underline-mode, text-underline-style, text-underline-width, unicode-range.
• Replaced the propertyList export, which was an object, with the propertyDefinitions export, which is a Map containing similar information. (However, the extended property is removed from the values of the Map.)
• Improved generic parsing and serialization spec conformance, i.e. the code path used for non-special-cased CSS properties. (Notably including better case-sensitivity handling, which regressed in v5.3.6; see #303.)
• Updated the CSSStyleDeclaration class:
  • Removed the length setter.
  • Stopped attempting to "hide" underscored properties by making them non-enumerable.
• Various performance improvements.