JS: Support SpreadObjectProperty #103
Description
Starting with Rhino 1.9.0, the parser now supports SpreadObjectProperty, which is a spread operator inside of an object literal. Previusly, only ObjectProperty (a key/value pair) was supported.
When this library was updated to Rhino 1.9.0, I made the minor changes necessary to support the AST changes, but SpreadObjectPropertys are currently silently ignored. This keeps the library functionally equivalent to what it was before, but we're missing the ability to glean info out of this newly-supported syntax.
This PR is to update JavaScriptOutlineTree (the component impacted here) to support SpreadObjectProperty properly.
See #102 for when this library was updated from Rhino 1.8.0 -> 1.9.0.