Re: [csswg-drafts] [selectors] Add :role() pseudo-class (#3596)

@bkardell wrote:
> the computed role is sometimes involves fairly complex checking and tree walking.

As one example this complexity, review [`AccessibilityTable:isDataTable()` in the WebKit source](https://github.com/WebKit/webkit/blob/master/Source/WebCore/accessibility/AccessibilityTable.cpp#L112). 

In addition to hierarchical validation and well-formedness (`<tables>` do not get the table _role_ unless they have a valid grid of rows and cells), this method checks for a variety of style-based heuristics such as borders and zebra-striped row colors. It's determining layout-vs-data table based on the style characteristics, which then determine the role, and would only then affect the cascade for a `:role()` selector.

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Received on Monday, 4 February 2019 08:18:59 UTC