setBlurOffsets = function (filterElem, stdDev) {
  if (stdDev > 3) {
    // TODO: Create algorithm here where size is based on expected blur
    svgCanvas.assignAttributes(filterElem, {
      x: '-50%',
      y: '-50%',
      width: '200%',
      height: '200%'
    }, 100)
  } else {
    filterElem.removeAttribute('x')
    filterElem.removeAttribute('y')
    filterElem.removeAttribute('width')
    filterElem.removeAttribute('height')
  }
}
Sets the `x`, `y`, `width`, `height` values of the filter element in order to
make the blur not be clipped. Removes them if not neeeded.
@function module:svgcanvas.SvgCanvas#setBlurOffsets
@param {Element} filterElem - The filter DOM element to update
@param {Float} stdDev - The standard deviation value on which to base the offset size
@returns {void}