Finish up conversion and convert TBody

addon/-private/utils/default-to.js

@@ -0,0 +1,37 @@
+import { computed } from '@ember/object';
+
+let VALUES = new WeakMap();
+
+function valuesFor(obj) {
+  if (!VALUES.has(obj)) {
+    VALUES.set(obj, Object.create(null));
+  }
+
+  return VALUES.get(obj);
+}
+
+export default function defaultTo(defaultValue) {
+  return computed({
+    get(key) {
+      let values = valuesFor(this);
+
+      if (!(key in values)) {
+        values[key] = typeof defaultValue === 'function' ? defaultValue() : defaultValue;
+      }
+
+      return defaultValue;
+    },
+
+    set(key, value) {
+      let values = valuesFor(this);
+
+      if (value === undefined) {
+        values[key] = typeof defaultValue === 'function' ? defaultValue() : defaultValue;
+      } else {
+        values[key] = value;
+      }
+
+      return values[key];
+    },
+  });
+}

addon/components/ember-table/component.js

@@ -78,23 +78,22 @@ export default Component.extend({
       }
     }
 
-    super.willDestroyElement(...arguments);
+    this._super(...arguments);
   },
 
   tableStyle: computed('tableWidth', function() {
     return htmlSafe(`width: ${this.get('tableWidth')}px;`);
   }),
 
-
   api: computed(function() {
     return {
       columns: null,
-      registerColumnTree: this.registerColumnTree,
+      registerColumnTree: this.registerColumnTree.bind(this),
       tableId: this.elementId,
     };
   }),
 
-  registerColumnTree() {
+  registerColumnTree(columnTree) {
     this.set('api.columnTree', columnTree);
-  }
+  },
 });