**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 <div>{context.text}</div>;
      }
      Grandchild.contextTypes = {text: PropTypes.string};
      const Child = props => <Grandchild />;
      const e = await render(<PurpleContext><Child /></PurpleContext>);
      expect(e.textContent).toBe('purple');
    });
    itRenders('a child context overriding a parent context', async render => {
      const Grandchild = (props, context) => {
        return <div>{context.text}</div>;
      };
      Grandchild.contextTypes = {text: PropTypes.string};
      const e = await render(
        <PurpleContext><RedContext><Grandchild /></RedContext></PurpleContext>,
      );
      expect(e.textContent).toBe('red');
    });
    itRenders('a child context merged with a parent context', async render => {
      class Parent extends React.Component {
        getChildContext() {
          return {text1: 'purple'};
        }
        render() {
          return <Child />;
        }
      }
      Parent.childContextTypes = {text1: PropTypes.string};
      class Child extends React.Component {