Use Node 10 and npm 6 for development

[etpinard]

... and Chrome 68 on CI.

Node 10 will become LTS in October, but why wait?

Switching to Node 10 makes us the latest major npm version with improved package-lock and faster installs and the latest v8 engine, speeding up our builds and CI runs (e.g. the build job on CI runs 30s faster, syntax is 30s faster too).

The switch to Chrome 68 appears to make two tests consistently fail:

The second one is probably related to #2747 (we might need to put a @noCI tag on that one).

[etpinard]

cc @alexcjohnson

[alexcjohnson]

Huh... the first test failure is just a slightly different rounding result - should be able to just increase the tolerance. But the second, we still have the explicit timezone-setting step:

But this is apparently not being honored by Chrome? There must be some other way to get it to use a timezone...

I see two timezone switches in the chrome flags:
--disable-per-user-timezone
--disable-system-timezone-automatic-detection
Hard to tell if one of those would get us back to the previous behavior of "just look at /etc/localtime" but we could try.

Actually, looking at where that page got its info from, maybe this is the new one that would help us:
--disable-fine-grained-time-zone-detection

[alexcjohnson]

Whew, fixing the timezone issue was harder than it should have been, thanks for persevering there! This looks great. 💃
Oddly though, it seems like a wash in terms of total test time - build is faster but test-jasmine and test-jasmine2 are both slower... oh well, still better to be up to date.

[etpinard]

but test-jasmine and test-jasmine2 are both slower.

Interesting. I guess Chrome 68 is slower than Chrome 64?