fix: Deal with undetected timeZone in Stats.js

[petetnt]

As seen in facebook/create-react-app#7783 (comment) (and GoogleChrome/lighthouse#1056 and others) if for some reasons the timeZone is undetected the locale-methods throw with "RangeError: Unsupported time zone specified undefined"

The issue itself was fixed in NodeJS 12, but affects other NodeJS LTS versions (6, 8, 10)

What kind of change does this PR introduce?

This PR deals with the issue similar to https://github.com/GoogleChrome/lighthouse/pull/1086/files and https://github.com/GoogleChrome/lighthouse/pull/1086/files

Did you add tests for your changes?

This is bit tricky to test this as it needs OS level changes or ENV variable setup at launch but manual steps to test this is

nvm install 10 # install affected version with nvm
nvm use 10 # checkout the node version

then reverse this check so that the locale time strings are run on the basic tests

if (!typeof obj.builtAt === "number") {

then run the basic tests

yarn test:basic

See all the snapshot tests failing 👀 and then run the tests again with Etc/Unknown timezone

TZ=Etc/Unknown yarn test:basic

Expected:

• All the snapshot tests fail again 👀

Actual:

    RangeError: Unsupported time zone specified undefined
        at new DateTimeFormat (native)
        at Date.toLocaleDateString (native)

Apply the changes from this branch to confirm that the issue was fixed.

Does this PR introduce a breaking change?

Nope, it just fixes an unfortunate edge case

What needs to be documented once your changes are merged?

No need for doc changes

Signed-off-by: petetnt pete.a.nykanen@gmail.com

[webpack-bot]

For maintainers only:

• This need to be documented (issue in webpack/webpack.js.org will be filed when merged)

[webpack-bot]

Thank you for your pull request! The most important CI builds succeeded, we’ll review the pull request soon.

[webpack-bot]

It looks like this Pull Request doesn't include enough test cases (based on Code Coverage analysis of the PR diff).

A PR need to be covered by tests if you add a new feature (we want to make sure that your feature is working) or if you fix a bug (we want to make sure that we don't run into a regression in future).

@petetnt Please check if this is appliable to your PR and if you can add more test cases.

Read the test readme for details how to write test cases.

[sokra]

Thanks