Spec link:

  https://tc39.github.io/proposal-bigint/#sec-serializejsonproperty

Thanks to André Bargull for the test:

  https://bugzilla.mozilla.org/show_bug.cgi?id=1528784

https://github.com/tc39/ecma262/pull/1433

This makes v8's _monkeyYaml happy --- without it, the info block never ends, and we fail to parse the `features` key.

An explicit indentation marker isn't used because monkeyYaml doesn't supported it, and adding it might slightly slow things down.

Using PyYAML instead was considered, but after trying it, I don't think it looks viable. [simple test cases](https://gist.github.com/caitp/4a59a67f671907c11051a1b7bd5fdaae)

- Changes associated with spec changes (tc39/proposal-string-matchall#41)
- Update spec comments
- Added test verifying error thrown when `regexp[Symbol.matchAll]` is not callable
- Added test verifying `ToString` is called on `receiver`

https://github.com/tc39/ecma262/pull/1340

- `Proxy/getOwnPropertyDescriptor/call-parameters.js`
  Fixes a call to `Object.getOwnPropertyDescriptor` without the prop
  param. Not actually a huge problem, as the test wasn't depending on
  it.

- `Proxy/getOwnPropertyDescriptor/result-type-is-not-object-nor-undefined`
  This test asserted that `function() {}` should throw with the
  following spec step, which is incorrect, as functions are typed as
  `Object` in the spec.
  """
  1. If Type(trapResultObj) is neither Object nor Undefined, throw a
    TypeError exception.
  """

Migrating all tests to this API is necessary to prevent tests from hanging indefinitely when a SAB is sent to a worker but the code in the worker attempts to create a non-sharable TypedArray (something that is not Int32Array or BigInt64Array). When that scenario occurs, an exception is thrown and the agent worker can no longer communicate with any other threads that control the SAB. If the main thread happens to be spinning in the $262.agent.waitUntil() while loop, it will never meet its termination condition and the test will hang indefinitely.

Because we've defined $262.agent.broadcast(SAB) in https://github.com/tc39/test262/blob/master/INTERPRETING.md, there are host implementations that assume compatibility, which must be maintained.

Migrating all tests to this API is necessary to prevent tests from hanging indefinitely when a SAB is sent to a worker but the code in the worker attempts to create a non-sharable TypedArray (something that is not Int32Array or BigInt64Array). When that scenario occurs, an exception is thrown and the agent worker can no longer communicate with any other threads that control the SAB. If the main thread happens to be spinning in the $262.agent.waitUntil() while loop, it will never meet its termination condition and the test will hang indefinitely.

Because we've defined $262.agent.broadcast(SAB) in https://github.com/tc39/test262/blob/master/INTERPRETING.md, there are host implementations that assume compatibility, which must be maintained.

Previously, these tests simply compared against an equivalent regular expression pattern by generating a large string containing either all code points up to U+FFFF or U+10FFFF, depending on the `u` flag, and then performing:

    str.replace(re, '') === str.replace(otherRe, '');

These two `String#replace` calls can be optimized into a single `RegExp#test` call by following the pattern used in the property escapes tests at https://github.com/mathiasbynens/unicode-property-escapes-tests.