Broken, but checkpoint editor/graph/layout split

EditorGroup.js

@@ -51,10 +51,6 @@ class EditorGroup extends EditorEntryBase {
     return lines;
   }
 
-  clear() {
-    super.clear();
-  }
-
   getNodes() {
     return this.nodes_.getEntries();
   }
@@ -72,10 +68,6 @@ class EditorGroup extends EditorEntryBase {
     return this.elem_;
   }
 
-  getCollection() {
-    return new Collection(this.nodes);
-  }
-
   onInputKeyDown(e) {
     switch (e.key) {
       case 'Enter':