Sizzle: update 2.1.1
Authors: Update AUTHORS.txt and .mailmap
Build: account for version labels in Sizzle versions

Fixes gh-1939
Build: update node dependencies
Build: Sizzle version labels must start with a dash
Event: add test for window scrollTop/Left logic in iframes

Ref d21edb599d8f5f80a3f3ecba5b62311b9cd1a3e6
CSS: Add unit tests for negative margins and positioning

Ref 1b932bb7867924b98529537f8ccd35db979ae22a
Manipulation: make wrapAll funarg execute only once

Ref 359b03cac74d7336676a6992f14b7ccab9b28659
Traversing: simplify jQuery#contents method

Ref 90d7cc1d8b2ea7ac75f0eacb42439349c9c73278
CSS: simplify "defaultDisplay" module

Ref 90d7cc1d8b2ea7ac75f0eacb42439349c9c73278