Follow up from https://github.com/facebook/react/pull/11616.

Here's one I found. These two invariants:

https://github.com/facebook/react/blob/7e7127387ba64f57299eaff8656542cea6fb3a2d/packages/react-reconciler/src/ReactFiberClassComponent.js#L330-L343

are in a function that's behind a DEV block:

https://github.com/facebook/react/blob/7e7127387ba64f57299eaff8656542cea6fb3a2d/packages/react-reconciler/src/ReactFiberClassComponent.js#L447-L449

I don't think this is intentional, but need to verify.

There may be more. I'll use this issue to track while https://github.com/facebook/react/pull/11616 preserves existing behavior.
itRenders('boolean prop with zero value', async render => {
        const e = await render(<div hidden={0} />);
        expect(e.getAttribute('hidden')).toBe(null);
      });
      itRenders('no boolean prop with null value', async render => {
        const e = await render(<div hidden={null} />);
        expect(e.hasAttribute('hidden')).toBe(false);
      });
    });
    describe('download property (combined boolean/string attribute)', function() {
      itRenders('download prop with true value', async render => {
        const e = await render(<a download={true} />);
        expect(e.getAttribute('download')).toBe('');
      });
      itRenders('download prop with false value', async render => {
        const e = await render(<a download={false} />);
        expect(e.getAttribute('download')).toBe(null);
      });
      itRenders('download prop with string value', async render => {
        const e = await render(<a download="myfile" />);
        expect(e.getAttribute('download')).toBe('myfile');
      });
      itRenders('download prop with string "false" value', async render => {
        const e = await render(<a download="false" />);
        expect(e.getAttribute('download')).toBe('false');
      });
      itRenders('download prop with string "true" value', async render => {
        const e = await render(<a download={'true'} />);
        expect(e.getAttribute('download')).toBe('true');
      });