shadow dom support

[yashaka]

reference:

• https://github.com/KnowledgeExpert/selenidejs/pull/130/files
• and probably something from here
  • https://github.com/KnowledgeExpert/selenidejs/pull/129/files

[aleksandr-kotlyar]

Found same feature request earlier #214

As known selenide has shadow dom support starting from version 5.10.0
It would be great to implement the same feature in selene.

selenide/selenide#1090

fixes:
selenide/selenide#1129

I suggest one of them can be closed.

[aleksandr-kotlyar]

Selenide 5.18.0 has released recursive search in shadow-dow which is faster than it has before.
Can be helpful and useful in selene too.
News here: https://selenide.org/2021/01/23/selenide-5.18.0/
PR here: selenide/selenide#1373
Script here: https://github.com/selenide/selenide/blob/master/src/main/resources/find-in-shadow-roots.js

[yashaka]

this feature needs some kine of "js selectors", let's think on allowing something like browser.element('js:document.querySelector(".foo")'), etc...

[yashaka]

Changed label from 2.0-mandatory to 2.0-desired, because the main support is already provided...
And next items are "a plus" not "a must" from now:

• alignment with Selenide optimisation
  • (yet not sure if we really need it, not sure that it's relevant to our case)
• maybe some smart "implicit search" inside shadow roots
  • (looks like the selenide's implementation still is not fully implicit)
• maybe some "web-only" alternative to browser and element, that allow to access shadow without query, i.e. element.shadow_root or element.shadow...

So, they can be implemented even after 2.0