**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`
type="checkbox"
              defaultChecked={false}
              checked={true}
              readOnly={true}
            />,
            1,
          );
          expect(e.checked).toBe(true);
          expect(e.getAttribute('defaultChecked')).toBe(null);
        },
      );
    });
    describe('textareas', function() {
      
      
      itRenders('a textarea with a value and an onChange', async render => {
        const e = await render(<textarea value="foo" onChange={() => {}} />);
        
        
        expect(e.getAttribute('value')).toBe(null);
        expect(e.value).toBe('foo');
      });
      itRenders('a textarea with a value and readOnly', async render => {
        const e = await render(<textarea value="foo" readOnly={true} />);
        
        
        expect(e.getAttribute('value')).toBe(null);
        expect(e.value).toBe('foo');
      });
      itRenders(