**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`
}
            },
          };
        },
      };
      let e = await render(threeDivIterable);
      let parent = e.parentNode;
      expect(parent.childNodes.length).toBe(3);
      expect(parent.childNodes[0].tagName).toBe('DIV');
      expect(parent.childNodes[1].tagName).toBe('DIV');
      expect(parent.childNodes[2].tagName).toBe('DIV');
    });
    itRenders('emptyish values', async render => {
      let e = await render(0);
      expect(e.nodeType).toBe(TEXT_NODE_TYPE);
      expect(e.nodeValue).toMatch('0');
      
      
      expect((await render(<div>{''}</div>)).textContent).toBe('');
      expect(await render([])).toBe(null);
      expect(await render(false)).toBe(null);
      expect(await render(true)).toBe(null);
      expect(await render(undefined)).toBe(null);
      expect(await render([[[false]], undefined])).toBe(null);
    });
  });
  describe('property to attribute mapping', function() {
    describe('string properties', function() {
      itRenders('simple numbers', async render => {
        const e = await render(<div width={30} />);