**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
for (styleName in lastProp) {
            if (
              lastProp.hasOwnProperty(styleName) &&
              (!nextProp || !nextProp.hasOwnProperty(styleName))
            ) {
              if (!styleUpdates) {
                styleUpdates = {};
              }
              styleUpdates[styleName] = '';
            }
          }
          
          for (styleName in nextProp) {
            if (
              nextProp.hasOwnProperty(styleName) &&
              lastProp[styleName] !== nextProp[styleName]
            ) {
              if (!styleUpdates) {
                styleUpdates = {};
              }
              styleUpdates[styleName] = nextProp[styleName];
            }
          }
        } else {