add test for null content in dojox.atom.io.model.js

[Jared Jurkiewicz]

in dojox.atom.io.model.js there is a call to the unescape function for html content but there is no check for a null value

if(lowerType === "html"

lowerType === "text/html"

lowerType === "xhtml"

lowerType

"text/xhtml"){

this.value = dojox.atom.io.model.util.unEscapeHtml(this.value);

Should be: this.value = this.value?dojox.atom.io.model.util.unEscapeHtml(thi s.value):"";