Remove special handling for getSelection() with Firefox from tests

[whimboo]

We got https://bugzilla.mozilla.org/show_bug.cgi?id=85686 in Firefox fixed for version 138 which is currently in Nightly. That means that we no longer need to special-case the handling for getSelection() with Firefox.

I assume this PR needs to wait with getting merged until Firefox 138 is going to be released?

[sefeng211]

It's Nightly only feature for now, I plan to give it some time before enabling it. So we should only remove the special-case handling after it's enabled in Release

[whimboo]

Oh, good point. Lets move this PR to draft for now.

[whimboo]

Enabling by default for all Firefox builds is covered by https://bugzilla.mozilla.org/show_bug.cgi?id=1954979.

[github-actions]

Test results for "tests 1"

4 failed
❌ [firefox-page] › tests/page/elementhandle-select-text.spec.ts:20:3 › should select textarea @firefox-ubuntu-22.04-node18
❌ [firefox-page] › tests/page/elementhandle-select-text.spec.ts:33:3 › should select input @firefox-ubuntu-22.04-node18
❌ [firefox-page] › tests/page/locator-misc-2.spec.ts:76:3 › should select textarea @firefox-ubuntu-22.04-node18
❌ [firefox-page] › tests/page/retarget.spec.ts:212:3 › input value retargeting @firefox-ubuntu-22.04-node18

4 flaky

⚠️ [firefox-page] › tests/page/page-evaluate.spec.ts:403:3 › should throw for too deep reference chain @firefox-ubuntu-22.04-node18
⚠️ [webkit-library] › tests/library/trace-viewer.spec.ts:773:1 › should handle src=blob @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-screenshot.spec.ts:345:5 › page screenshot › should work while navigating @webkit-ubuntu-22.04-node18
⚠️ [playwright-test] › tests/ui-mode-test-watch.spec.ts:145:5 › should watch all @windows-latest-node18-1

38780 passed, 808 skipped
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Merge workflow run.