Remove babel polyfill dependency of babel-node

[bdwain]

Q	A
Fixed Issues?	Fixes #10295
Patch: Bug Fix?	Yes
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link	N/A
Any Dependency Changes?	Using core-js 3 and regenerator runtime instead of babel polyfill
License	MIT

Since babel polyfill is deprecated, I removed the usage of it in babel/node. Instead, I switched it to use core-js@3 and regenerator-runtime (as suggested). Behavior is unchanged.

Note that one test seems to fail when running all tests, but not when running tests only for babel-node with TEST_ONLY. But this happens on the latest master too, so I assume it's unrelated to my change.

 ● bin/babel-node › node_--inspect

    Timeout - Async callback was not invoked within the 10000ms timeout specified by jest.setTimeout.Error: 

      199 |       }
      200 | 
    > 201 |       it(testName, buildTest(binName, testName, opts));
          |       ^
      202 |     });
      203 |   });
      204 | });

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/11546/

[nicolo-ribaudo]

Thanks!