getHeight = function(oldVal, newVal) {
          if ( oldVal !== newVal) {
            rebuildStyles = true;
          }
          return newVal;
        }
@ngdoc function
@name refreshCanvas
@methodOf ui.grid.class:Grid
@description Builds all styles and recalculates much of the grid sizing
@param {object} buildStyles optional parameter.  Use TBD
@returns {promise} promise that is resolved when the canvas
has been refreshed