FLUID-4817: Use small button icons in IE8
FLUID-4817: Add small icons for captions button (in case we get captions working in IE8)
Merge remote-tracking branch 'anastasia/FLUID-4817'

* anastasia/FLUID-4817:
  FLUID-4817: Add small icons for captions button (in case we get captions working in IE8)
  FLUID-4817: Use small button icons in IE8