**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`
expect(e.getAttribute('textLength')).toBe('10');
      });
      itRenders('no badly cased aliased SVG attribute alias', async render => {
        const e = await render(<text strokedasharray="10 10" />, 1);
        expect(e.hasAttribute('stroke-dasharray')).toBe(false);
        expect(e.getAttribute('strokedasharray')).toBe('10 10');
      });
      itRenders(
        'no badly cased original SVG attribute that is aliased',
        async render => {
          const e = await render(<text stroke-dasharray="10 10" />, 1);
          expect(e.getAttribute('stroke-dasharray')).toBe('10 10');
        },
      );
    });
    describe('unknown attributes', function() {
      itRenders('unknown attributes', async render => {
        const e = await render(<div foo="bar" />);
        expect(e.getAttribute('foo')).toBe('bar');
      });
      itRenders('unknown data- attributes', async render => {
        const e = await render(<div data-foo="bar" />);
        expect(e.getAttribute('data-foo')).toBe('bar');
      });
      itRenders('badly cased reserved attributes', async render => {
        const e = await render(<div CHILDREN="5" />, 1);
        expect(e.getAttribute('CHILDREN')).toBe('5');
      });
      itRenders('"data" attribute', async render => {