### 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_
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
  function isFiberMountedImpl(fiber: Fiber): number {
    let node = fiber;
    let prevNode = null;
    if (!fiber.alternate) {
       I
       y
      if ((getFiberFlags(node) & Placement) !== NoFlags) {
        return MOUNTING;
      }
       T
      if ((getFiberFlags(node) & Incomplete) !== NoFlags) {
        return UNMOUNTED;
      }
      while (node.return) {
        prevNode = node;
        node = node.return;
        if ((getFiberFlags(node) & Placement) !== NoFlags) {
          return MOUNTING;
        }
         T
        if ((getFiberFlags(node) & Incomplete) !== NoFlags) {
          return UNMOUNTED;
        }
         I
        const isTimedOutSuspense =
          node.tag === SuspenseComponent && node.memoizedState !== null;
        if (isTimedOutSuspense) {
           N