Update CodeMirror to 5.18.2

Highlights include:
  - Make sure gutter backgrounds stick to the rest of the gutter during
    horizontal scrolling.
  - JavaScript mode: Fix some small parsing bugs and improve TypeScript
    support.
  - The "jade" mode has been renamed to "pug".

Change-Id: I5079f75490586aec851d5cf99860a91b1a5d590b

gerrit-gwtui/src/main/java/net/codemirror/mode/ModeInfo.java

@@ -82,7 +82,6 @@ public class ModeInfo extends JavaScriptObject {
       Modes.I.htmlmixed(),
       Modes.I.http(),
       Modes.I.idl(),
-      Modes.I.jade(),
       Modes.I.javascript(),
       Modes.I.jinja2(),
       Modes.I.jsx(),
@@ -110,6 +109,7 @@ public class ModeInfo extends JavaScriptObject {
       Modes.I.powershell(),
       Modes.I.properties(),
       Modes.I.protobuf(),
+      Modes.I.pug(),
       Modes.I.puppet(),
       Modes.I.python(),
       Modes.I.q(),

gerrit-gwtui/src/main/java/net/codemirror/mode/Modes.java

@@ -67,7 +67,6 @@ public interface Modes extends ClientBundle {
   @Source("htmlmixed.js") @DoNotEmbed DataResource htmlmixed();
   @Source("http.js") @DoNotEmbed DataResource http();
   @Source("idl.js") @DoNotEmbed DataResource idl();
-  @Source("jade.js") @DoNotEmbed DataResource jade();
   @Source("javascript.js") @DoNotEmbed DataResource javascript();
   @Source("jinja2.js") @DoNotEmbed DataResource jinja2();
   @Source("jsx.js") @DoNotEmbed DataResource jsx();
@@ -95,6 +94,7 @@ public interface Modes extends ClientBundle {
   @Source("powershell.js") @DoNotEmbed DataResource powershell();
   @Source("properties.js") @DoNotEmbed DataResource properties();
   @Source("protobuf.js") @DoNotEmbed DataResource protobuf();
+  @Source("pug.js") @DoNotEmbed DataResource pug();
   @Source("puppet.js") @DoNotEmbed DataResource puppet();
   @Source("python.js") @DoNotEmbed DataResource python();
   @Source("q.js") @DoNotEmbed DataResource q();