Saxon » SaxonJS

Following on from https://saxonica.plan.io/issues/3501 - where we dealt with IXSL extension functions; there are a few minor corrections to make for the IXSL extension instructions ixsl:set-attribute, ixsl:remove-attribute, and ixsl:set-style.

We should check that current context item is an Element in ixsl:remove-attritube and ixsl:set-attribute (throwing an error if not). We currently only check that the context item is in the HTML page. Similarly, we should check that the object supplied as the 3rd arg to ixsl:set-style is an Element, and that the style property is available, producing an error if not (to correspond with ixsl:set-property).