Cleanup via JSHint

[OlsonDev]

• Add missing semi-colons
• Remove redundant semi-colons
• Don't redeclare variables

Things I didn't take care of:

• Use === to compare with 0; I would in my own projects though
• Use === to compare with null; both places would then need || thing === undefined, not a fan of that
• Wrap for...in bodies in hasOwnProperty checks; there were a lot of them but I assume prototype chain should be respected in all
• __proto__ is deprecated; seems to be used properly
• Function constructor is a form of eval; yeah, well...
• Remove 10 unused variables: prop, object, obs, observer, target, callback, skipChanges, changeRecords (x2), array; besides prop they're all argument names. prop is used in the objectIsEmpty function and can't be removed

[jmesserly]

Awesome! LGTM! Good choices on those skipped ones.

Use === to compare with 0; I would in my own projects though

yeah, === 0 would be fine with me, FWIW

Use === to compare with null; both places would then need || thing === undefined, not a fan of that

agreed, I'm not a fan either.

__proto__ is deprecated; seems to be used properly

fwiw, it's been sort-of un-deprecated now that it's specified in ES6 and so it'll be available across all engines: http://www.ecma-international.org/ecma-262/6.0/#sec-object.prototype.__proto__ ... though maybe Object.getPrototypeOf would be cleaner though.