Throw missing await error on expect.poll

[moufmouf]

Hey!

First of all, thanks for this library, it saved my life when I was desperate to find an issue with a Playwright test. Good job, really.

Here is a proposal for a possible improvement:

The expect.poll method can be used to query arbitrary data (not necessarily locators) and in this case, any method called after expect should probably raise a warning.

For instance:

expect.poll(() => { /* some code */ }).toContain('foo');

should probably raise an eslint error about a missing await.

Right now, it is not raising an error, because toContain is not in the list of checked methods for expect.

[mskelton]

Thanks for reporting this! This will be included in the next release of the plugin.