conformance: normalized WPT% => 91.4%. Nesting 1, Variables 1, and Typed OM math

[paulirish]

Advances conformance across 7 W3C Web Platform Test (WPT) suites in pure Node.js, achieving a +91.4% normalized pass rate across 16,842 feasible tests (+883 net passing assertions).

Key Capabilities & Spec Alignments

• CSS Nesting Level 1 (css-nesting):

  • Implemented CSSNestedDeclarations serialization, omitting empty wrapper blocks per § 4.1.
  • Added relative combinator desugaring for leading combinators (& + .bar, & > .baz) per § 3.
  • Propagated outer rule.selectorText mutations dynamically into nested child rules referencing &.
  • Restricted & nesting scope to CSSStyleRule parents, preventing spurious & prefixes inside grouping rules (@media, @supports).

• CSS Variables Level 1 & Cascade Level 5 (css-variables):

  • Implemented revert and revert-layer cascade fallback rollback when referenced variables are unassigned.
  • Implemented dependency cycle detection for self, 2-node, and multi-node dependency chains (guaranteed-invalid).
  • Preserved single-space tokenization for empty custom property definitions (--foo: ; vs --foo:;).
  • Integrated SVG presentation attributes (alignment-baseline, baseline-shift, flood-color, lighting-color, stop-color, clip-rule) into getCascadedStyle variable substitution.

• CSS Values Level 4 & CSS Typed OM Level 1 (css-typed-om):

  • Simplified calculation trees: combined same-unit numeric literals in min()/max() and distributed negation over CSSMathSum.
  • Implemented indexed property proxy setters (array[array.length] = item) on CSSUnparsedValue and CSSTransformValue.
  • Preserved case sensitivity for custom properties during StylePropertyMap validation.

• CSSOM Core & Condition Rules (cssom):

  • Introduced CSSConditionRule base class for CSSMediaRule, CSSSupportsRule, and CSSContainerRule with conditionText.
  • Added containerName and containerQuery properties on CSSContainerRule.
  • Reconciled specified declaration order in CSSStyleDeclaration._addDeclaration per cssom-1 § 6.4.1.
  • Enforced strict shorthand getPropertyValue completeness checks.

• DOMMatrix & W3C Geometry Interfaces (src/DOMMatrix.ts):

  • Implemented 0-allocation in-place 2D affine fast paths (multiplySelf, rotateSelf, translateSelf, scaleSelf, invertSelf, transformPoint).
  • Replaced unrolled matrix math with compact 2-loop dot products and 2x2 block Laplace expansion for inversion, correctly handling NaN and singular determinants.
  • Eliminated double-transposition cloning overhead in constructors and deduplicated prototype getters.

• Spec-Driven Automation & Harness Safety:

  • Extracted cascade initial values, SVG presentation attributes, and color properties dynamically from @webref/css and mdn-data into src/data/gen/cascade-data.ts.
  • Hardened parallel WPT runner against memory leaks with dual-tier /proc/[pid]/stat RSS watchdogs, state D detection, and mandatory --max-old-space-size=1024 enforcement across 24 worker pools.

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Technical Breakdown by Module

Module	Core Changes
src/cascade.ts	Added cycle graph detection in substituteVariables; implemented revert / revert-layer cascade rollback; wired generated SVG presentation attributes and default values.
src/CSSOM.ts	Added CSSConditionRule inheritance; updated CSSContainerRule, CSSMediaRule, and CSSSupportsRule; implemented empty CSSNestedDeclarations serialization omission and ancestor-scoped nesting checks.
src/CSSStyleDeclaration.ts	Aligned specified declaration order in _addDeclaration; implemented strict shorthand getPropertyValue / getPropertyPriority completeness.
src/DOMMatrix.ts	Added in-place 2D affine fast paths; optimized 4x4 matrix multiplication; refactored invertMatrix to block Laplace expansion; deduplicated prototype getters.
src/math-parser.ts	Added same-unit combining in simplifyMinMax; added negation distribution over CSSMathSum.
src/typed-om.ts	Added indexed append proxy setters on CSSUnparsedValue and CSSTransformValue; preserved custom property case in StylePropertyMap.
src/parser.ts	Desugared leading combinators in nested selector parsing; preserved empty custom property whitespace tokens; rejected unknown at-rules in declaration blocks.
scripts/codegen/	Added generate_cascade_data.ts consuming @webref/css and mdn-data to emit src/data/gen/cascade-data.ts.
scripts/wpt/node/	Added V8 memory limits, state-D watchdog polling via /proc/[pid]/stat, and synchronized 16,842 feasible denominator baseline.