angularjs - 角度でクラスとコメントのディレクティブがバインドされないのはなぜですか?

Question

プランカー: http://plnkr.co/edit/XBJjr6uR1rMAg3Ng7DiJ?p=preview

これら2つは同じように見えると思います：

<span dt-attrib="{{person.name}}">This won't be here</span><br/>
<span class="dt-class: {{person.name}};">This won't be here.</span> - this does not process

しかし、これは私が得るものです：

This text was set by the dtAttrib directive, value="Burt Finklestein"
This text was set by the dtClass directive, value="{{person.name}}"

コード：

app.directive("dtAttrib", function() {
    return {
        restrict: "A",
        link: function(scope, element, attrs) {
            element.text('This text was set by the dtAttrib directive' + DisplayValueString(attrs.dtAttrib));
            }
        }
    }
});

app.directive("dtClass", function() {
    return {
        restrict: "C",
        link: function(scope, element, attrs) {
            element.text('This text was set by the dtClass directive' + DisplayValueString(attrs.dtClass));
        }
    };
});