browser: Add frameLocator() method

[pkalsi97]

What?

This PR Add frameLocator() method to Page, Frame, Locator, and FrameLocator objects. This is a shorthand for locator(selector).contentFrame() providing a more concise API for working with iframes.

Usage

  // Before
  const frame = page.locator('#my-iframe').contentFrame();
  const button = frame.locator('#submit-btn');

  // After
  const button = page.frameLocator('#my-iframe').locator('#submit-btn');

 // Nested iframes are also supported:
  page.frameLocator('#outer').frameLocator('#inner').locator('button')

Why?

Issue #5177 Describes the need for a convince method.

Checklist

• I have performed a self-review of my code.
• I have commented on my code, particularly in hard-to-understand areas.
• I have added tests for my changes.
• I have run linter and tests locally (make check) and all pass.

Checklist: Documentation (only for k6 maintainers and if relevant)

Please do not merge this PR until the following items are filled out.

• I have added the correct milestone and labels to the PR.
• I have updated the release notes: link
• I have updated or added an issue to the k6-documentation: grafana/k6-docs#NUMBER if applicable
• I have updated or added an issue to the TypeScript definitions: grafana/k6-DefinitelyTyped#NUMBER if applicable

Related PR(s)/Issue(s)

Closes #5177

[ankur22]

LGTM 🚀 Thanks for this change!

Left some minor things that would be good if they were addressed but functionally looks correct to me.

[pkalsi97]

@ankur22 Thanks for the review, i have addressed the above. :)

i have two concerns

1. browser: add page.on('requestfinished') event handler #5486 this PR introduced the page.on('requestfinished') , but some how the ci did not catch the lint issue now that lint issue is showing up in this branch as well as it was updated.

Running linters...
internal/js/modules/k6/browser/browser/page_mapping.go:645:5: missing cases in switch of type common.PageEventName: common.PageEventRequestFinished (exhaustive)
                                switch event {
                                ^
1 issues:
* exhaustive: 1
make: *** [lint] Error 1

2. I would request you to block the merger of browser: address frameLocator PR review comments #5489 to prevent big conflict, merge this one first when ever you see fit.