make markdown error handling js-specific

IPython/frontend/html/notebook/static/css/notebook.css

@@ -389,6 +389,6 b' pre, code, kbd, samp { white-space: pre-wrap; }'
     font-family: monospace;
 }
 
-.render-error {
+.js-error {
     color: darkred;
 }
  No newline at end of file

IPython/frontend/html/notebook/static/js/textcell.js

@@ -223,9 +223,9 b' var IPython = (function (IPython) {'
             try {
                 this.set_rendered(html);
             } catch (e) {
-                console.log("Error rendering Markdown:");
+                console.log("Error running Javascript in Markdown:");
                 console.log(e);
-                this.set_rendered($("<div/>").addClass("render-error").html(
+                this.set_rendered($("<div/>").addClass("js-error").html(
                     "Error rendering Markdown!<br/>" + e.toString())
                 );
             }