**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`
'an input value overriding defaultValue no matter the prop order',
        async render => {
          const e = await render(
            <input defaultValue="bar" value="foo" readOnly={true} />,
            1,
          );
          expect(e.value).toBe('foo');
          expect(e.getAttribute('value')).toBe('foo');
          expect(e.getAttribute('defaultValue')).toBe(null);
        },
      );
    });
    describe('checkboxes', function() {
      itRenders('a checkbox that is checked with an onChange', async render => {
        const e = await render(
          <input type="checkbox" checked={true} onChange={() => {}} />,
        );
        expect(e.checked).toBe(true);
      });
      itRenders('a checkbox that is checked with readOnly', async render => {
        const e = await render(
          <input type="checkbox" checked={true} readOnly={true} />,
        );
        expect(e.checked).toBe(true);
      });
      itRenders(
        'a checkbox that is checked and no onChange/readOnly',
        async render => {