**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 {foo: 'bar'};
          }
        }
        return render(<MyComponent />);
      },
      'MyComponent.getChildContext(): childContextTypes must be defined ' +
        'in order to use getChildContext().',
    );
    itThrowsWhenRendering(
      'if getChildContext returns a value not in childContextTypes',
      render => {
        class MyComponent extends React.Component {
          render() {
            return <div />;
          }
          getChildContext() {
            return {value1: 'foo', value2: 'bar'};
          }
        }
        MyComponent.childContextTypes = {value1: PropTypes.string};
        return render(<MyComponent />);
      },
      'MyComponent.getChildContext(): key "value2" is not defined in childContextTypes.',
    );
  });
  describe('refs', function() {
    it('should not run ref code on server', async () => {
      let refCount = 0;
      class RefsComponent extends React.Component {