function PropertyValueIterator(value){

    /** 
     * Iterator value
     * @type int
     * @property _i
     * @private
     */
    this._i = 0;
    
    /**
     * The parts that make up the value.
     * @type Array
     * @property _parts
     * @private
     */
    this._parts = value.parts;
    
    /**
     * Keeps track of bookmarks along the way.
     * @type Array
     * @property _marks
     * @private
     */
    this._marks = [];
    
    /**
     * Holds the original property value.
     * @type parserlib.css.PropertyValue
     * @property value
     */
    this.value = value;
    
}
A utility class that allows for easy iteration over the various parts of a
property value.
@param {parserlib.css.PropertyValue} value The property value to iterate over.
@namespace parserlib.css
@class PropertyValueIterator
@constructor