Need pass through for newly supported placeholder pseudo-element / classes

TRINIDAD-2170 provided pass through support for implicit pseudo-classes / elements in general, and thereby allowed supporting placeholder text styling.

There has been since then few changes in how browsers support this styling:
1. FF changed this from pseudo-class to pseudo-elements
https://developer.mozilla.org/en-US/docs/Web/CSS/::-moz-placeholder
https://bugzilla.mozilla.org/show_bug.cgi?id=737786

2. IE started supporting
http://msdn.microsoft.com/en-us/library/ie/hh772745(v=vs.85).aspx

We need to adapt to these changes now.