provide default values as zero, starting to work
provide default values as zero, starting to work

When attempts to read the bounds rect dimension using D3 .attr() return
null, substitute a zero value that can be used in calculations a little
more readily.

Starting with this commit, the plugin now works when bounds are
provided as an associative array and the browser supports foreignObject!

citizencode/d3textwrap,fuzzthink/d3textwrap,vijithassar/d3textwrap