Usually, we can just chain two locators with `>>` to implement
`Locator.locator(locator)`. However, this does not play nicely with more
advanced inner locators like `or` and `and`:
```ts
const child = page.locator('input').or(page.locator('button'));
page.locator('parent').locator(child);
```
One would expect the above to locate "input or button" inside a
"parent". However, currently it locates "input inside a parent" or
"button", because it's translated to `parent >> input >>
internal:or="button"`.
To fix this, we have to wrap inner locator into `internal:chain` and
query it separately from the parent.
Fixes#23724.
- Rename internal selectors `has`, `control` and `attr` to
`internal:has`, `internal:control` and `internal:attr`.
- Fix `getByLabel()` to respect strictness, by introducing
`internal:label` selector.
- Move tests essential for ports to `selectors-by.spec`.
This fixes a few issues:
- strict mode was producing false negatives if multiple query paths
lead to the same element being picked;
- in some cases the number of intermediate items in the list was
exponential and crashed quickly.
What changed:
- `visible` engine is a real engine now;
- `capture` selectors are transformed to `has=` selectors for
easier implementation;
- chained querying switched from a list to a set to avoid
exponential size.
This introduces `locator('div', { has: locator })` syntax that matches elements containing other elements.
Can be used together with `hasText`.
Internally, has selector engine takes an inner selector escaped with double-quotes:
`div >> has="li >> span >> text=Foo" >> span`.
