Ajax: Remove workaround for IE6/7

(cherry-picked from e5190982c40d7ac8ab9bdb2e7e4334f0e123ef66)

Closes gh-1597
Ref #8138
Data: avoid non-alphanumeric chars in expando properties

(cherry-picked from 0cdec797de23555c95a70978f4d9e06f3b041330)

Ref chromium issue 378607
Ref #14839
Closes gh-1662
Ajax: remove event dependency from the ajax module

(cherry-picked from 4e7f34f6296111f7f91d621397dfb02c6bf4c41f)

Closes gh-1695
CSS: Clean up memory leak in reliableMarginRight

(cherry-picked from 7d15b4d1f181de8868c375c545a51e4dfc28a611)

Fixes gh-1795
Closes gh-1893

Thanks for the report flexphperia!