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

**What is the current behavior?**
I've started recieving this warning about my SVGs which is using [feGaussianBlur](https://developer.mozilla.org/en-US/docs/Web/SVG/Element/feGaussianBlur): 
`Warning: Expected server HTML to contain a matching <feGaussianBlur> in <filter>.`

**What is the expected behavior?**
Should be no warnings because there are no difference.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
Such behavior started right after updating to `React 16.0.0-rc.3` and never happened with `React 15.6.1`
return renderIntoDom(element, div, false, errorCount);
};
const clientRenderOnServerString = async (element, errorCount = 0) => {
  const markup = await renderIntoString(element, errorCount);
  resetModules();
  var domElement = document.createElement('div');
  domElement.innerHTML = markup;
  let serverNode = domElement.firstChild;
  const firstClientNode = await renderIntoDom(
    element,
    domElement,
    true,
    errorCount,
  );
  let clientNode = firstClientNode;
  
  while (serverNode || clientNode) {
    expect(serverNode != null).toBe(true);
    expect(clientNode != null).toBe(true);
    expect(clientNode.nodeType).toBe(serverNode.nodeType);
    
    
    
    expect(serverNode === clientNode).toBe(true);
    serverNode = serverNode.nextSibling;
    clientNode = clientNode.nextSibling;
  }
  return firstClientNode;
};
function BadMarkupExpected() {}