Ignore abstract methods when decorating class (#11345)

* Ignore abstract methods when decorating class

* Address Nico's feedback

* Add input/output test

* Update test output to account for _nonIterableRest changes

packages/babel-helper-create-class-features-plugin/src/decorators.js

@@ -128,7 +128,10 @@ export function buildDecoratedClass(ref, path, elements, file) {
 
   const classDecorators = takeDecorators(node);
   const definitions = t.arrayExpression(
-    elements.map(extractElementDescriptor.bind(file, node.id, superId)),
+    elements
+      // Ignore TypeScript's abstract methods (see #10514)
+      .filter(element => !element.node.abstract)
+      .map(extractElementDescriptor.bind(file, node.id, superId)),
   );
 
   let replacement = template.expression.ast`