Electron upgrade

[flotwig]

• Closes Cypress headless hangs in second spec after previous goes back in history #5475
• Closes Upgrade Electron to 7.1.4 #5852

User facing changelog

• Upgraded Electron from 5.0.10 to 7.1.4. This bumps the internal Node version to 12.8.1 and the internal Chromium version to 78.0.3904.113.

Additional details

• depends on Decaf server automation code and related tests #5850 getting merged - most of the diff is this

How has the user experience changed?

PR Tasks

• Have tests been added/updated?
• Has the original issue been tagged with a release in ZenHub?

[cypress-bot]

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PR Review Checklist

If any of the following requirements can't be met, leave a comment in the review selecting 'Request changes', otherwise 'Approve'.

User Experience

• The feature/bugfix is self-documenting from within the product.
• The change provides the end user with a way to fix their problem (no dead ends).

Functionality

• The code works and performs its intended function with the correct logic.
• Performance has been factored in (for example, the code cleans up after itself to not cause memory leaks).
• The code guards against edge cases and invalid input and has tests to cover it.

Maintainability

• The code is readable (too many nested 'if's are a bad sign).
• Names used for variables, methods, etc, clearly describe their function.
• The code is easy to understood and there are relevant comments explaining.
• New algorithms are documented in the code with link(s) to external docs (flowcharts, w3c, chrome, firefox).
• There are comments containing link(s) to the addressed issue (in tests and code).

Quality

• The change does not reimplement code.
• There's not a module from the ecosystem that should be used instead.
• There is no redundant or duplicate code.
• There are no irrelevant comments left in the code.
• Tests are testing the code’s intended functionality in the best way possible.

Internal

• The original issue has been tagged with a release in ZenHub.

[cypress]

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Test summary

3573 • 0 • 47 • 0

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Run details

Project	cypress
Status	Passed
Commit	decb35b
Started	Dec 11, 2019 3:59 PM
Ended	Dec 11, 2019 4:04 PM
Duration	05:02 💡
OS	Linux Debian - 9.11
Browser	Multiple

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[jennifer-shehane]

Is this PR updating the Node version? Aren't we using 12.0.0, don't we want to test against that?

Also, if this is a convenience thing - probably highlights why our docker images combinations are problematic for our own users. :P

[flotwig]

This PR updates the bundled Node version to 12.8.1 (Electron 5 -> 7). The node version we use in CI needs to match this, since the unit + integrations tests (of Electron code) all run in node in CI, not electron. We could use electron-mocha to eliminate this requirement, but currently that's the way it is.