**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`
render() {
          
          return <div>{this.context.text}</div>;
        }
      }
      const e = await render(
        <PurpleContext><ClassChildWithoutContext /></PurpleContext>,
      );
      expect(e.textContent).toBe('');
    });
    itRenders('stateless child without context', async render => {
      function StatelessChildWithoutContext(props, context) {
        
        return <div>{context.text}</div>;
      }
      const e = await render(
        <PurpleContext><StatelessChildWithoutContext /></PurpleContext>,
      );
      expect(e.textContent).toBe('');
    });
    itRenders('class child with wrong context', async render => {
      class ClassChildWithWrongContext extends React.Component {