Remove left/right autocomplete navigation for MessageEditor

src/components/views/elements/MessageEditor.js

@@ -116,10 +116,6 @@ export default class MessageEditor extends React.Component {
                     autoComplete.onUpArrow(event); break;
                 case "ArrowDown":
                     autoComplete.onDownArrow(event); break;
-                case "ArrowLeft":
-                    autoComplete.onLeftArrow(event); break;
-                case "ArrowRight":
-                    autoComplete.onRightArrow(event); break;
                 case "Tab":
                     autoComplete.onTab(event); break;
                 case "Escape":

src/editor/autocomplete.js

@@ -63,14 +63,6 @@ export default class AutocompleteWrapperModel {
         this._getAutocompleterComponent().moveSelection(+1);
     }
 
-    onLeftArrow() {
-        this._getAutocompleterComponent().moveSelection(-1);
-    }
-
-    onRightArrow() {
-        this._getAutocompleterComponent().moveSelection(+1);
-    }
-
     onPartUpdate(part, offset) {
         // cache the typed value and caret here
         // so we can restore it in onComponentSelectionChange when the value is undefined (meaning it should be the typed text)