Introduce new extended attribute grammars

[lukewarlow]

Introduce four new extended attribute grammars

These new grammars will be used by the HTML spec for attribute reflection extended attributes. ExtendedAttributeString ([Reflect="foo"]), ExtendedAttributeInteger ([ReflectDefault=1]), ExtendedAttributeDecimal ([ReflectDefault=1.0]) and ExtendedAttributeIntegerList ([ReflectRange=(1,100)]) are added.

• At least two implementers are interested (and none opposed):
  • …
  • …
• Tests are written and can be reviewed and commented upon at:
  • N/A
• Implementation bugs are filed:
  • Chromium: N/A
  • Gecko: N/A
  • WebKit: N/A
  • Deno: N/A
  • Node.js: N/A
  • webidl2.js: New extended attribute grammars w3c/webidl2.js#817
  • widlparser: 4 new Extended Attribute grammars being added plinss/widlparser#91
• MDN issue is filed: N/A
• The top of this comment includes a clear commit message to use.

(See WHATWG Working Mode: Changes for more details.)

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[domenic]

Looks good with nit, although I presume we shouldn't merge this until we're sure they're going to be used.

[lukewarlow]

I presume we shouldn't merge this until we're sure they're going to be used.

Yeah I think it makes sense to wait until at least the non-enum IDL reflection stuff is agreed upon. That uses all 3 of these new grammars.