Improved applyAncestorBiasScore performance

Deprecated updateDescendantWithAncestorBias, moved policy lookup to
scoreElement, greatly improved applyAncestorBiasScore performance
Improved scoreElement performance

Minor changes to applyAncestorBiasScore. Moved regular expression to
constant outside of applyAttributeScore. Inlined applyTagNameScore and
deprecated the function. Some optimization of applyTextScore.
scoreElement now only does one call to getDescriptor
Improved scoreElement performance

Inlined applyAncestorBiasScore and deprecated the function, inlined
applyAttributeScore and deprecated the function
Improved applyTextScore perf

Setting the branch property on the element (an expando) was having a
surprisingly negative performance impact, so I removed it.
Improved preformatted propagation

Reverted back to using querySelectorAll
Removed preformatted expando

Switched to using WeakSet
Implemented collectPreformatted
Refactored charCount expando

Uses new features map (WeakMap)