Arrows Not Working

There is at least one case when arrows don't work, similar to #78.

This looks to be Raphael issue, the cause is `` tag in HTML document's header.

In SVG arrows (_markers_) are drawn in background like `background: url(#marker-bla-bla-bla);`, which references another element where the marker is defined `` tag is used, this messes up the the background URL reference by fragment.

Start by reproducing the arrow failure in a document that uses a tag, then trace how Raphael renders SVG markers and resolves the fragment in the background URL. The issue mentions no files or tests, so first locate the marker-rendering entry point and verify that arrows work with and without before defining the fix.

Written by the indexing model from the issue text.