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

Report a bug.

**What is the current behavior?**

Whenever I render SVG elements that are camel cased (e.g. `<linearGradient />`) on the server side,  I get the following warning:

```
Warning: <linearGradient /> is using uppercase HTML. Always use lowercase HTML tags in React.
```

**What is the expected behavior?**

Warnings should be consistent with the client side rendering, if possible. In this case, I'd expect no warning, since using camel cased SVG element names is pretty standard.

For client side rendering, there seems to be a check for the current namespace:

https://github.com/facebook/react/blob/efcac24af26afba90e2ef525509ca40f3bd6f270/src/renderers/dom/fiber/ReactDOMFiberComponent.js#L344-L352

For server side rendering, there seems to be currently no such check in place:

https://github.com/facebook/react/blob/81706eeb7a51c1cea7fd8e66733a4f4618155ef5/src/renderers/shared/server/ReactPartialRenderer.js#L537-L544

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

Hitting this on 16.0.0-beta.5. Was not hitting it on 15.6.1, the version I was previously on.

Thanks in advance.
this._updateDOMChildren(lastProps, nextProps, transaction, context);
    switch (this._tag) {
      case 'input':
        
        
        
        ReactDOMInput.updateWrapper(this);
        
        
        inputValueTracking.updateValueIfChanged(getNode(this));
        break;
      case 'textarea':
        ReactDOMTextarea.updateWrapper(this);
        break;
      case 'select':
        
        
        transaction.getReactMountReady().enqueue(postUpdateSelectWrapper, this);
        break;
    }
  },
  /**
   * Reconciles the properties by detecting differences in property values and
   * updating the DOM as necessary. This function is probably the single most
   * critical path for performance optimization.
   *
   * TODO: Benchmark whether checking for changed values in memory actually
   *       improves performance (especially statically positioned elements).
   * TODO: Benchmark the effects of putting this at the top since 99% of props
   *       do not change for a given reconciliation.