Created by: andrewhubbs
IE 9 will return a null for offsetWidth and offsetHeight when the element is an SVG element.
The result is a NaN error when trying to do arithmetic with a null value when calculating the left/top values for the tooltip placement.
This fix is not perfect because it can result in an off center positioning, but it corrects the error where the top/left CSS will be set to 0 due to a NaN error in the math.