https://github.com/tc39/proposal-intl-segmenter/pull/55

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.
  """