Fix CodeMirror line numbers

The line numbers in CodeMirror editor could show incorrectly because of
the overflow-wrap: break-word introduced in 26d7e2f.

Set the normal overflow-wrap on the editor to prevent this problem.

Author: atw

html/css/ejs.css

@@ -326,6 +326,7 @@ blockquote footer:before {
   height: auto;
   line-height: 1.35;
   border-top: 1px solid #4ab;
+  overflow-wrap: normal;
 }
 .CodeMirror-scroll {
   max-height: 700px;