TocJS processing

The tocjs transformation was originally created as a plug-in that was distributed outside of the toolkit, but it now ships bundled in the default packages. This HTML5-based output type creates a JavaScript-based frameset with TOC entries that expand and collapse.

The following Ant targets control most of the TocJS processing:
Sets up default properties. This target detects whether builds have already specified a name for JavaScript control file; if not, the default name toctree.js is used.
Calls the target, which generates the contents frame for TocJS output.
Ensures that the HTML5 processing module is run. If scripts are missing required information, such as a name for the default frameset, this target copies default style and control files. This target was add to the DITA-OT in version 1.5.4; earlier versions of the TocJS transformation created only the JavaScript control file by default.