### Website or app

google.com

### Repro steps

This started after last update 4.20.0
![image](https://user-images.githubusercontent.com/11052469/137713404-e6702959-7870-46a6-8566-4cfe61d25309.png)
![image](https://user-images.githubusercontent.com/11052469/137713464-c5e478d2-4e9e-4ee4-abdf-83d23c04704b.png)


### 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_
window.postMessage(
    {
      source: 'react-devtools-content-script',
      hello: true,
    },
    '*',
  );
}
function handleMessageFromDevtools(message) {
  window.postMessage(
    {
      source: 'react-devtools-content-script',
      payload: message,
    },
    '*',
  );
}
function handleMessageFromPage(evt) {
  if (
    evt.source === window &&
    evt.data &&
    evt.data.source === 'react-devtools-bridge'
  ) {
    backendInitialized = true;
    port.postMessage(evt.data.payload);
  }
}
function handleDisconnect() {