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(
        'a div with multiple children separated by whitespace',
        async render => {
          const e = await render(
            <div id="parent">
              <div id="child1" /> <div id="child2" />
            </div>,
          );
          expect(e.id).toBe('parent');
          let child1, child2, textNode;
          expect(e.childNodes.length).toBe(3);
          child1 = e.childNodes[0];
          textNode = e.childNodes[1];
          child2 = e.childNodes[2];
          expect(child1.id).toBe('child1');
          expect(child1.childNodes.length).toBe(0);
          expectTextNode(textNode, ' ');
          expect(child2.id).toBe('child2');
          expect(child2.childNodes.length).toBe(0);
        },
      );
      itRenders(
        'a div with a single child surrounded by whitespace',
        async render => {
          
          const e = await render(<div id="parent">  <div id="child" />   </div>); 
          let textNode1, child, textNode2;
          expect(e.childNodes.length).toBe(3);
          textNode1 = e.childNodes[0];
          child = e.childNodes[1];