Vector: Workaround for legacy IE font-sizing issues

In IE <= 7, 'Ctrl' + '+' scales the font size in far too large steps if the
root element's font size is given in the 'em' unit. Everything becomes normal
if the root element's font-size is given in '%'. This should not have any
effect in other browsers.

Bug: 24515
Change-Id: I5cc864d73935a02713075840b7ff80000b3ae88a
Merge "Vector: Workaround for legacy IE font-sizing issues"