ST6RI-766 Updated mode_template.js for xtext_grammar_converter.

- Also removed support for highlighting in classic Jupyter Notebook
(i.e., not Jupyter Lab).

Author: seidewitz

org.omg.sysml.jupyter.jupyterlab/src/main/mode.ts

@@ -23,9 +23,6 @@
  *   $GIT_REPO_DIR/tool-support/syntax-highlighting/jupyter/mode_template.ts
  */
 
-// tslint:disable-next-line
-//import 'codemirror/addon/mode/simple';
-
 import {StringStream} from "@codemirror/language"
 import { clike } from '@codemirror/legacy-modes/mode/clike';
 
@@ -90,4 +87,4 @@ export const sysmlparser = clike({
             },
         },
     }
-);
+);