InlineEdit: Add Sublime Text keymap

Sublime Text keymap has been available since CodeMirror 4.0. This change
enables using it in the EditScreen.

Change-Id: I34e82fceb9502405d8d03a6c6117d4900d08248e

gerrit-gwtui/src/main/java/com/google/gerrit/client/editor/EditPreferencesBox.java

@@ -321,6 +321,9 @@ public class EditPreferencesBox extends Composite {
     keyMap.addItem(
         KeyMapType.EMACS.name().toLowerCase(),
         KeyMapType.EMACS.name());
+    keyMap.addItem(
+        KeyMapType.SUBLIME.name().toLowerCase(),
+        KeyMapType.SUBLIME.name());
     keyMap.addItem(
         KeyMapType.VIM.name().toLowerCase(),
         KeyMapType.VIM.name());