**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`
} else {
          expect(parent.childNodes.length).toBe(3);
          expectTextNode(parent.childNodes[0], 'a');
          expectTextNode(parent.childNodes[1], 'b');
          expectTextNode(parent.childNodes[2], 'c');
        }
      });
    });
    describe('escaping >, <, and &', function() {
      itRenders('>,<, and & as single child', async render => {
        const e = await render(<div>{'<span>Text&quot;</span>'}</div>);
        expect(e.childNodes.length).toBe(1);
        expectNode(e.firstChild, TEXT_NODE_TYPE, '<span>Text&quot;</span>');
      });
      itRenders('>,<, and & as multiple children', async render => {
        const e = await render(
          <div>{'<span>Text1&quot;</span>'}{'<span>Text2&quot;</span>'}</div>,
        );
        if (
          render === serverRender ||
          render === clientRenderOnServerString ||
          render === streamRender
        ) {
          expect(e.childNodes.length).toBe(3);
          expectTextNode(e.childNodes[0], '<span>Text1&quot;</span>');
          expectTextNode(e.childNodes[2], '<span>Text2&quot;</span>');
        } else {
          expect(e.childNodes.length).toBe(2);
          expectTextNode(e.childNodes[0], '<span>Text1&quot;</span>');
          expectTextNode(e.childNodes[1], '<span>Text2&quot;</span>');