Don't coerce parameters to string #175
Description
In the xsltProcess method the expressionContext is populated by the parameters from this.options.parameters. However all parameters are coerced into StringValue. While in XPath 2 you can test the type with instance of and typeswitch, the most useful parameter to be blocked by this coercion are node parameters, already supported in XPath 1. In particular the ability to hand over additional documents as parameters is powerful and supported by e.g. Firefox.