**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`
bareElement = <div id="foobarbaz" />;
        });
        it('should reconnect ES6 Class to ES6 Class', () =>
          expectMarkupMatch(
            <ES6ClassComponent id="foobarbaz" />,
            <ES6ClassComponent id="foobarbaz" />,
          ));
        it('should reconnect Pure Component to ES6 Class', () =>
          expectMarkupMatch(
            <ES6ClassComponent id="foobarbaz" />,
            <PureComponent id="foobarbaz" />,
          ));
        it('should reconnect Bare Element to ES6 Class', () =>
          expectMarkupMatch(<ES6ClassComponent id="foobarbaz" />, bareElement));
        it('should reconnect ES6 Class to Pure Component', () =>
          expectMarkupMatch(
            <PureComponent id="foobarbaz" />,
            <ES6ClassComponent id="foobarbaz" />,
          ));
        it('should reconnect Pure Component to Pure Component', () =>
          expectMarkupMatch(
            <PureComponent id="foobarbaz" />,
            <PureComponent id="foobarbaz" />,
          ));
        it('should reconnect Bare Element to Pure Component', () =>
          expectMarkupMatch(<PureComponent id="foobarbaz" />, bareElement));
        it('should reconnect ES6 Class to Bare Element', () =>
          expectMarkupMatch(bareElement, <ES6ClassComponent id="foobarbaz" />));
        it('should reconnect Pure Component to Bare Element', () =>
          expectMarkupMatch(bareElement, <PureComponent id="foobarbaz" />));