**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.value).toBe('Hello');
          
          e.value = 'Goodbye';
          ReactTestUtils.Simulate.change(e);
          expect(changeCount).toBe(1);
          expect(e.value).toBe('Goodbye');
        });
        itClientRenders('a controlled textarea', async render => {
          let changeCount = 0;
          const e = await render(
            <ControlledTextArea onChange={() => changeCount++} />,
          );
          expect(changeCount).toBe(0);
          expect(e.value).toBe('Hello');
          
          e.value = 'Goodbye';
          ReactTestUtils.Simulate.change(e);
          expect(changeCount).toBe(1);
          expect(e.value).toBe('Goodbye');
        });
        itClientRenders('a controlled checkbox', async render => {
          let changeCount = 0;
          const e = await render(
            <ControlledCheckbox onChange={() => changeCount++} />,
          );
          expect(changeCount).toBe(0);
          expect(e.checked).toBe(true);
          
          e.checked = false;
          ReactTestUtils.Simulate.change(e);