Install regional browser locale data

[tnsardesai]

summary

• install tzdata and locales in headful and headless browser images
• generate the US, UK, Canadian, Irish, and Singapore English POSIX locales
• add Chrome locale resource aliases for the English locales Chrome does not package separately

why

Browser VMs need timezone data for process-level TZ handling and generated locales for LANG/LC_ALL. Chrome also needs a matching locale resource pack or it falls back to a packaged locale.

tests

• built the complete headless Docker image
• verified all generated locales and Chrome locale packs inside the image
• launched headless Chrome with Asia/Singapore / en-SG and verified the JavaScript timezone, Intl locale, and navigator language

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Note

Low Risk
Docker image build-only changes with no application code paths; the en-GB locale alias is a pragmatic fallback that could differ slightly from native Chrome packs for those regions.

Overview
Headful and headless Chromium browser images now bake in timezone data and English regional locale support so VMs can honor process TZ and LANG/LC_ALL without falling back to minimal container defaults.

Both Dockerfiles install locales and tzdata, then locale-gen for en_US, en_GB, en_CA, en_IE, and en_SG UTF-8. After Chrome for Testing is unpacked, en-GB.pak is copied to en-CA, en-IE, and en-SG locale resource files so Chrome finds a matching pack for locales it does not ship separately.

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