### Website or app

https://codesandbox.io/s/react-playground-forked-j4niq

### Repro steps

Emoji seem supported but produce strange symbole

![image](https://user-images.githubusercontent.com/24865815/133793744-55a55582-90ad-425f-8a40-4c061a3c1d80.png)

To test emoji on Window Os, use `[win]+[.]` 🟩


### How often does this bug happen?

Every time

### DevTools package (automated)

_No response_

### DevTools version (automated)

_No response_

### Error message (automated)

_No response_

### Error call stack (automated)

_No response_

### Error component stack (automated)

_No response_

### GitHub query string (automated)

_No response_
const primaryChildFragment = node.child;
          const fallbackChildFragment = primaryChildFragment
            ? primaryChildFragment.sibling
            : null;
          if (prevNode !== fallbackChildFragment) {
            return UNMOUNTED;
          }
        }
      }
    } else {
      while (node.return) {
        node = node.return;
      }
    }
    if (node.tag === HostRoot) {
       T
       r
      return MOUNTED;
    }
     I
     t
    return UNMOUNTED;
  }
   This function is copied from React and should be kept in sync:
   https:github.com/facebook/react/blob/main/packages/react-reconciler/src/ReactFiberTreeReflection.js
   It would be nice if we updated React to inject this function directly (vs just indirectly via findDOMNode).
   BEGIN copied code
  function findCurrentFiberUsingSlowPathById(id: number): Fiber | null {
    const fiber = idToArbitraryFiberMap.get(id);
    if (fiber == null) {