BigInt test plan

• BigInt literals
  • invalid digits [merged, merged]
• Type conversion
  • ToPrimitive [merged]
  • ToBoolean [merged, more testing PR (rejected)]
  • ToNumber [merged]
  • ToString [merged]
  • ToObject [merged]
  • ToNumeric [some testing merged, more testing PR (rejected)]
  • RequireObjectCoercible [merged]
• Testing/comparison
  • relational comparison <, <=, >, >= [merged, merged, could also use bigint-and-string tests]
  • equality ==, !=, ===, !== [merged, deleted, merged]
• Expressions
  • increment/decrement [merged]
  • typeof [PR]
  • prefix +
  • negation [merged]
  • bitwise operators &, |, ^, ~ (@thejoshwolfe)
  • shifts <<, >>, >>> (@thejoshwolfe)
  • arithmetic operators
    • addition
    • subtraction
    • multiplication
    • division
    • modulo
    • exponentiation
• BigInt object
  • constructor
  • property descriptor (@thejoshwolfe)
  • parseInt (@cxielarko)
  • asUintN [merged]
  • asIntN [merged]
  • prototype
    • attributes
    • constructor [PR]
    • toLocaleString (@thejoshwolfe)
    • toString [merged, missing coverage]
    • valueOf (@thejoshwolfe)
• JSON.stringify
• Number constructor [merged]
• TypedArrays
  • BigInt64Array
  • BigUint64Array
• DataViews
  • DataView.prototype.getBigInt64 [PR]
  • DataView.prototype.getBigUint64 (@cxielarko)
  • DataView.prototype.setBigInt64 [branch not yet submitted as PR]
  • DataView.prototype.setBigUint64 (@cxielarko)
• feature declaration (@thejoshwolfe)
• Recent spec changes (@cxielarko) [PR, merged]