add test and fix for string literal case (#10578)

packages/babel-plugin-proposal-decorators/src/transformer-legacy.js

@@ -281,7 +281,10 @@ export default {
     path.replaceWith(
       t.callExpression(state.addHelper("initializerDefineProperty"), [
         t.cloneNode(path.get("left.object").node),
-        t.stringLiteral(path.get("left.property").node.name),
+        t.stringLiteral(
+          path.get("left.property").node.name ||
+            path.get("left.property").node.value,
+        ),
         t.cloneNode(path.get("right.arguments")[0].node),
         t.cloneNode(path.get("right.arguments")[1].node),
       ]),

packages/babel-plugin-proposal-decorators/test/fixtures/legacy-class-prototype-properties/string-literal-properties/exec.js

@@ -0,0 +1,29 @@
+function dec(target, name, descriptor) {
+  expect(target).toBeTruthy();
+  expect(typeof name).toBe("string");
+  expect(typeof descriptor).toBe("object");
+
+  target.decoratedProps = (target.decoratedProps || []).concat([name]);
+
+  return descriptor;
+}
+
+class Example {
+  @dec "a-prop";
+}
+
+let inst = new Example();
+
+expect(Example.prototype).toHaveProperty("decoratedProps");
+expect(inst.decoratedProps).toEqual([
+  "a-prop"
+]);
+
+expect(inst).toHaveProperty("a-prop");
+expect(inst["a-prop"]).toBeUndefined();
+
+const descs = Object.getOwnPropertyDescriptors(inst);
+
+expect(descs["a-prop"].enumerable).toBeTruthy();
+expect(descs["a-prop"].writable).toBeTruthy();
+expect(descs["a-prop"].configurable).toBeTruthy();