转义字符被吞得问题

传入一个带有转义字符的字符串作为方法参数，在qlexpress里面进行方法调用将字符串作为参数传入，转义符号会被吞。
简要代码 例：
expressRunner.addFunction(“hello”);
script=hello(“hello\nworld”)
expressRunner.excute(script);

在hello方法中接收换行字符串，结果字符串中的\被吞，只剩hellonworld

Start with the provided addFunction and excute reproduction, focusing on how the script parses the string argument "hello\nworld" before it reaches the hello method. Trace the string-argument parsing path and add a regression test for preserving the escape character; done means the method receives the intended newline string rather than "hellonworld".

Written by the indexing model from the issue text.