function addPrefix(name, obj) {
						if (typeof obj === 'string') {
							obj = { prefix: obj };
						}

						vendorPrefixes[name] = utils.extend({}, prefixObj, obj);
					}
Transforms snippet value if required. For example, this transformation
may add <i>!important</i> declaration to CSS property
@param {String} snippet
@param {Boolean} isImportant
@returns {String}