Fix 2 discrepancies from current JS standards

[xiehan]

No description provided.

[justinbach]

I'm all for the change from 2 to 4 tabs.

I think that the other rule is perhaps overly restrictive, because there are situations where declaring local variables inside of case conditions makes the code more readable. Perhaps we can modify the language to require curly braces around the block only when declaring branch-local variables, and otherwise not using them?

[xiehan]

@justinbach If you're okay with starting to enforce the second case, then it's fine with me. My biggest issue is that we already have a ton of code in place not enforcing that rule (especially in WWW, with all of the reducers), and it's useless to have rules that we're not going to enforce ourselves.