Fix test fails.
Ensure `_.at` and `_.pullAt` work with falsey `array` and `collection` values when keys are provided.
Fix `isArrayLike` in older IE.
Avoid testing `arguments` object constructor which may be `Array` in some old browsers.
Use the `new` operator to ensure constructors of other realms produce objects of those realms.
Ensure old Opera avoids a false positive for support of `isHostObject`.
Add more `_.assign`, `_.defaults`, `_.merge`, and `_.transform` tests.
Add `_.callback` test.
Remove `underscore` build config from Underscore tests.
Rebuild dist.
Remove `underscore` build test runs from travis.yml.
Remove `backbone` build from .gitignore.
Test order nits.
Add find method tests.
Cleanup assignment method tests.
Make lazy `_.drop` test more complex.
Fix _.keysIn for inherited non-enumerable props.
Add test for inherited shadowed props.
Ensure `_.keysIn` skips  inherited`constructor` properties.
Simplify lazy chaining.