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 [merged]
  • prefix +
  • negation [merged]
  • bitwise not [merged]
  • bitwise infix operators &, |, ^ [merged]
  • shifts <<, >>, >>> [merged]
  • unary minus [merged]
  • arithmetic operator type errors (@thejoshwolfe) [PR]
  • arithmetic operators (+, -, *, /, %, **) [merged]
  • operand coercion
• BigInt object
  • constructor
  • property descriptor (@thejoshwolfe)
  • parseInt [merged]
  • asUintN [merged]
  • asIntN [merged]
  • attributes [merged]
  • prototype
    • attributes
    • constructor [merged]
    • toLocaleString (@thejoshwolfe)
      • thisBigIntValue
    • toString [merged, missing coverage]
      • thisBigIntValue [merged]
    • valueOf [merged, merged]
• JSON.stringify
• Number constructor [merged]
• TypedArrays [merged, branch with additional coverage]
• DataViews
  • DataView.prototype.getBigInt64 [merged]
  • DataView.prototype.getBigUint64 (@cxielarko) [merged]
  • DataView.prototype.setBigInt64 [merged]
  • DataView.prototype.setBigUint64 (@cxielarko)
• feature declaration (@thejoshwolfe)
• Recent spec changes
  • JSON [merged]
  • boolean equality [merged]
  • atomic operations (@cxielarko) [PR]
  • ForceToBigInt/ForceToNumber coercion for TypedArrays
  • ForceToBigInt/ForceToNumber coercion for atomic operations
  • TypedArray sort method
  • TypedArray fill method
  • TypedArray set method
• Bugfixes
  • Missing lengths in Big(U)Int64Array constructor tests [issue reported by @jakobkummerow]
  • Restore Symbol.toStringTag property after verifyProperty [issue reported by @jakobkummerow]
  • Check toString result when Symbol.toStringTag property has been deleted