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.
{null}foo{null}
            {false}
          </div>,
        );
        expect(e.childNodes.length).toBe(1);
        expectTextNode(e.childNodes[0], 'foo');
      });
      itRenders('only null and false children as blank', async render => {
        const e = await render(
          <div>
            {false}
            {null}
            {null}
            {false}
          </div>,
        );
        expect(e.childNodes.length).toBe(0);
      });
    });
    describe('elements with implicit namespaces', function() {
      itRenders('an svg element', async render => {
        const e = await render(<svg />);
        expect(e.childNodes.length).toBe(0);
        expect(e.tagName).toBe('svg');
        expect(e.namespaceURI).toBe('http:www.w3.org/2000/svg');
      });
      itRenders('svg child element with an attribute', async render => {
        let e = await render(<svg viewBox="0 0 0 0" />);
        expect(e.childNodes.length).toBe(0);
        expect(e.tagName).toBe('svg');