nl_tokens: 把 StyleSheet 的内容转换成 css 字符串
pl_tokens: function styleSheetToString ( styleSheet ) { var result = "" ; var rules = styleSheet . cssRules , rule ; for ( var i = 0 ; i < rules . length ; i ++ ) { rule = rules [ i ] ; if ( rule instanceof CSSOM . CSSImportRule ) { result += styleSheetToString ( rule . styleSheet ) + '\n' ; } else { result += <mask> . cssText + '\n' ; } } return result ; }