Update minimum browser versions

[Gudahtt]

The minimum browser versions have been updated to Chromium v80 and Firefox v78.

Chromium v78 is >2 years old, and very few users use older versions than that.
Updated to v80 to provide support for optional chaining

Firefox v78 is the previous extended support release. The current Firefox extended support release is v91.

Related: #6805

Manual testing steps:

• Ensure that the extension still works on versions equal to or above the new minimum versions.

[metamaskbot]

Builds ready [f2800dd]

• builds: chrome, firefox, opera
• builds (beta): chrome, firefox, opera
• builds (flask): chrome, firefox, opera
• build viz: Build System
• code coverage: Report
• storybook: Storybook
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5, 6, 7, 8
  • common: 0, 1, 2, 3
  • content-script: 0
  • contentscript: contentscript
  • disable-console: disable-console
  • inpage: inpage
  • phishing-detect: phishing-detect
  • policy-load: policy-load
  • sentry-install: sentry-install
  • ui: 0, 1, 2, 3, 4, 5, 6, 7, 8

Page Load Metrics (858 ± 32 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	306	878	438	193	93
		domContentLoaded	774	1009	857	67	32
		load	775	1009	858	66	32
		domInteractive	774	1009	857	67	32

[Gudahtt]

Apparently this might affect up to 1% of the userbase, though it's likely a bit lower than that. More details here: #6805 (comment)

[Gudahtt]

I'm marking this as "DO-NOT-MERGE" for now, to give those away on holiday the chance to weigh in about whether we should do this now, or whether we should wait until after we add more in-app messaging asking users to update.

[darkwing]

Idea that @Gudahtt and I were discussing was parsing the UA and, if the user is stuck on an old browser, displaying a persistent message on top of the home screen to let the user know they wont receive MM updates. We'd need that to get merged the release before this gets merged.

[Gudahtt]

The issue #16283 has been created to track adding a notification warning users if we're about to drop support for their browser. That will unblock this PR.

[digiwand]

it appears the DO-NOT-MERGE tag was added for the last holiday season and can be removed now - LGTM! 🎄

[Gudahtt]

Thanks for the review @digiwand ! This was blocked by #16283, but is unblocked now that that has been included in the v10.26.0 RC.

[metamaskbot]

Builds ready [d6ccc71]

• builds: chrome, firefox
• builds (beta): chrome, firefox
• builds (flask): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4
  • common: 0, 1, 2, 3, 4, 5
  • content-script: 0
  • contentscript: contentscript
  • disable-console: disable-console
  • inpage: inpage
  • policy-load: policy-load
  • sentry-install: sentry-install
  • ui: 0, 1, 10, 11, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (1619 ± 61 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	101	153	124	17	8
		domContentLoaded	1280	1765	1592	116	56
		load	1280	1864	1619	127	61
		domInteractive	1280	1765	1592	116	56

Bundle size diffs [🚀 Bundle size reduced!]

• background: -592 bytes
• ui: -2763 bytes
• common: -304 bytes