## The current behavior

The full value of the `key` is very difficult / impossible to find and use in the interface of the React Devtools.

![Kapture 2020-04-22 at 11 47 47](https://user-images.githubusercontent.com/1935696/79997715-25222680-84ba-11ea-97ba-51f1679a8c91.gif)

Only managed to find it by accident :(

## The expected behavior

The `key` is visible in the props list to the right.

### Detailed Proposal

As mentioned below in https://github.com/facebook/react/issues/18702#issuecomment-617924196

Add a light divider and new section in the props panel to the right.

Potentially also add a question mark that shows an explanation about the fact that things in this section are not really props.

Ref (Original implementation): https://github.com/facebook/react-devtools/pull/328
case HostPortal:
      case HostText:
      case Fragment:
        return true;
      case HostRoot:
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        return false;
      default:
        const typeSymbol = getTypeSymbol(type);
        switch (typeSymbol) {
          case CONCURRENT_MODE_NUMBER:
          case CONCURRENT_MODE_SYMBOL_STRING:
          case DEPRECATED_ASYNC_MODE_SYMBOL_STRING:
          case STRICT_MODE_NUMBER:
          case STRICT_MODE_SYMBOL_STRING:
            return true;
          default:
            break;
        }
    }
    const elementType = getElementTypeForFiber(fiber);
    if (hideElementsWithTypes.has(elementType)) {
      return true;
    }
    if (hideElementsWithDisplayNames.size > 0) {
      const displayName = getDisplayNameForFiber(fiber);
      if (displayName != null) {
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        for (const displayNameRegExp of hideElementsWithDisplayNames) {
          if (displayNameRegExp.test(displayName)) {