**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
return;
    }
    didWarnInvalidHydration = true;
    var names = [];
    attributeNames.forEach(function(name) {
      names.push(name);
    });
    warning(false, 'Extra attributes from the server: %s', names);
  };
  var testDocument;
  
  
  var normalizeHTML = function(parent: Element, html: string) {
    if (!testDocument) {
      testDocument = document.implementation.createHTMLDocument();
    }
    var testElement = parent.namespaceURI === HTML_NAMESPACE
      ? testDocument.createElement(parent.tagName)
      : testDocument.createElementNS(
          (parent.namespaceURI: any),
          parent.tagName,