code: function getLayerDefsString_(defs) {
    var strDefs = '';
    for (var x in defs) {
      if (defs.hasOwnProperty(x)) {
        if (strDefs.length > 0) {
          strDefs += ';';
        }
        strDefs += (x + ':' + defs[x]);
      }
    }
    return strDefs;
  }
docs: get the layerdef text string from an object literal
  @param {Object} defs