Manipulation: make wrapAll funarg execute only once

Ref 359b03cac74d7336676a6992f14b7ccab9b28659
Traversing: simplify jQuery#contents method

Ref 90d7cc1d8b2ea7ac75f0eacb42439349c9c73278
Ref gh-1961
CSS: simplify "defaultDisplay" module

Ref 90d7cc1d8b2ea7ac75f0eacb42439349c9c73278
Ref gh-1961
CSS: simplify hack of css getter for the computed values

Ref gh-1906