**Do you want to request a *feature* or report a *bug*?**

Feature

**What is the current behavior?**

While server rendering React DOM and then hydrating with a different structure, React rightly warns that there are inconsistencies. But when I first saw these warnings I was not sure exactly what was going wrong.

Here are a few of the warnings I have been receiving:

```
Warning: Did not find a matching <button> in <div>.

Warning: Did not find a matching <img> in <div>.

Warning: Did not expect server HTML to contain a <div> in <div>.
```

Only on that last error did I catch on that this was a problem with server-rendering and the inconsistencies between that and my client render (intentional at the moment while testing some things in unpure render functions).

**What is the expected behavior?**

Being more explicit that this was a rendering inconsistency between server and client.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**

React v16-beta.1
if (didWarnInvalidHydration) {
      return;
    }
    didWarnInvalidHydration = true;
    warning(
      false,
      'Text content did not match. Server: "%s" Client: "%s"',
      serverText,
      clientText,
    );
  };
  var warnForPropDifference = function(
    propName: string,
    serverValue: mixed,
    clientValue: mixed,
  ) {
    if (didWarnInvalidHydration) {
      return;
    }
    didWarnInvalidHydration = true;
    warning(
      false,
      'Prop `%s` did not match. Server: %s Client: %s',
      propName,
      JSON.stringify(serverValue),
      JSON.stringify(clientValue),
    );
  };
  var warnForExtraAttributes = function(attributeNames: Set<string>) {
    if (didWarnInvalidHydration) {