test: compatible targets shouldn't insert regeneratorRuntime

- specifically, this checks that `--target node`, which targets Node 10
  right now, does not output regeneratorRuntime as generators have
  native support there (as does async/await)

- remove `targets` from `polyfill-regenerator` config because it's
  actually not necessary for this specific polyfill
  - it only inserts regenerator if a `regeneratorRuntime` global is
    detected, which is only inserted by
    `@babel/plugin-transform-generator` if the `targets` require it
    - meaning that for this particular polyfill, `preset-env`'s
      `targets` are sufficient

src/babelPluginTsdx.ts

@@ -78,7 +78,6 @@ export const babelPluginTsdx = babelPlugin.custom(() => ({
           name: 'babel-plugin-polyfill-regenerator',
           // don't pollute global env as this is being used in a library
           method: 'usage-pure',
-          targets: customOptions.targets,
         },
         {
           name: '@babel/plugin-proposal-class-properties',

test/e2e/tsdx-build-default.test.ts

@@ -59,6 +59,14 @@ describe('tsdx build :: zero-config defaults', () => {
     expect(matched).toBeTruthy();
   });
 
+  it('should not bundle regeneratorRuntime when targeting Node', () => {
+    const output = execWithCache('node ../dist/index.js build --target node');
+    expect(output.code).toBe(0);
+
+    const matched = grep(/regeneratorRuntime = r/, ['dist/build-default.*.js']);
+    expect(matched).toBeFalsy();
+  });
+
   it('should clean the dist directory before rebuilding', () => {
     let output = execWithCache('node ../dist/index.js build');
     expect(output.code).toBe(0);