FLUID-5320: Simplified getLineHeight and tests

Simplified the getLineHeight to just return the value from jQuery's css method. Refactored the tests to test for the multiplier in IE8 and IE9 and to test for pixel values elsewhere.
FLUID-5320: Fixed a typo in a comment
FLUID-5320: Renamed numerizeLineHeight

Renamed to getLineHeightMultiplier
Merge branch 'master' into FLUID-5320
Merge branch 'master' into FLUID-5320
FLUID-5320: Fixed typos
Merge remote-tracking branch 'justin/FLUID-5320'

* justin/FLUID-5320:
  FLUID-5320: Fixed typos
  FLUID-5320: Renamed numerizeLineHeight
  FLUID-5320: Fixed a typo in a comment
  FLUID-5320: Simplified getLineHeight and tests