Update for Playwright 1.39

[tmbrbr]

Merging with Firefox commit fdbb859

Updates to Firefox compatible with Playwright version 1.39 (Fixes #177)

[cla-assistant]

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1 out of 21 committers have signed the CLA.

✅ tmbrbr
❌ ffxbld
❌ Archaeopteryx
❌ Drekabi
❌ gregstoll
❌ aosmond
❌ emilio
❌ mkaply
❌ jandem
❌ hneiva
❌ KershawChang
❌ jcristau
❌ 92kns
❌ MReschenberg
❌ calixteman
❌ artines1
❌ makotokato
❌ dsmithpadilla
❌ mozkeeler
❌ dshin-moz
❌ jfx2006

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