[xhtml compat] Make sure linewap-padding is escaped

Closes #283

Author: marijnh

lib/codemirror.js

@@ -1371,10 +1371,10 @@ var CodeMirror = (function() {
       // Include extra text at the end to make sure the measured line is wrapped in the right way.
       if (options.lineWrapping) {
         var end = line.text.indexOf(" ", ch + 2);
-        extra = line.text.slice(ch + 1, end < 0 ? line.text.length : end + (ie ? 5 : 0));
+        extra = htmlEscape(line.text.slice(ch + 1, end < 0 ? line.text.length : end + (ie ? 5 : 0)));
       }
       measure.innerHTML = "<pre>" + line.getHTML(null, null, false, tabText, ch) +
-        '<span id="CodeMirror-temp-' + tempId + '">' + (line.text.charAt(ch) || " ") + "</span>" +
+        '<span id="CodeMirror-temp-' + tempId + '">' + htmlEscape(line.text.charAt(ch) || " ") + "</span>" +
         extra + "</pre>";
       var elt = document.getElementById("CodeMirror-temp-" + tempId);
       var top = elt.offsetTop, left = elt.offsetLeft;