Update the recommended invocation of `pip` to use the `python` command,
avoiding discrepancies on systems where the `pip` and `python` commands
are not provided by the same Python installation. In the interest of
consistency, also update the configuration for the project's continuous
integration service.

Recommend additional tooling for users with more advanced needs.

* [javascriptcore-test262-automation] Changes from https://github.com/webkit/webkit.git at sha 8a25978f29 on Tue Aug 28 2018 18:16:05 GMT+0000 (Coordinated Universal Time)

* [javascriptcore-test262-automation] Updated curation log with latest revision sha's from export and changed files.
    sourceRevisionAtLastExport: 8a25978f29 targetRevisionAtLastExport: 70dc3346

Import test changes from JavaScriptCore

[javascriptcore-test262-automation] Updated curation log with latest revision sha's from export and changed files.
    sourceRevisionAtLastExport: 12df785646 targetRevisionAtLastExport: 5032c509

[javascriptcore-test262-automation] Changes from https://github.com/webkit/webkit.git at sha 12df785646 on Mon Aug 27 2018 18:14:52 GMT+0000 (Coordinated Universal Time)

Import test changes from JavaScriptCore

[javascriptcore-test262-automation] Updated curation log with latest revision sha's from export and changed files.
    sourceRevisionAtLastExport: 93457d631e targetRevisionAtLastExport: 04c056b9

[javascriptcore-test262-automation] Changes from https://github.com/webkit/webkit.git at sha 93457d631e on Wed Aug 22 2018 18:13:32 GMT+0000 (Coordinated Universal Time)

Restore class field tests: public, private (+static)

Import test changes from JavaScriptCore

[javascriptcore-test262-automation] Updated curation log with latest revision sha's from export and changed files.
    sourceRevisionAtLastExport: ffc7368147 targetRevisionAtLastExport: ac84caea5

[javascriptcore-test262-automation] Changes from https://github.com/webkit/webkit.git at sha ffc7368147 on Tue Aug 21 2018 18:14:08 GMT+0000 (Coordinated Universal Time)

- needs to use async* to declare async generator methods.
- Needs to use yield* if delegating yield semantics are intended.
- Has assignment to private name method, which is not allowed and throws a TypeError at runtime.
- handle multiple $DONE calls
- fix calls to private methods

class-fields-public doesn't apply to all tests that are generated from these templates