**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`
<div>{'Text1'}{'Text3'}</div>,
        ));
      it('can explicitly ignore reconnecting different text', () =>
        expectMarkupMatch(
          <div>Text</div>,
          <div suppressHydrationWarning={true}>Other Text</div>,
        ));
      it('can explicitly ignore reconnecting different text in two code blocks', () =>
        expectMarkupMatch(
          <div suppressHydrationWarning={true}>{'Text1'}{'Text2'}</div>,
          <div suppressHydrationWarning={true}>{'Text1'}{'Text3'}</div>,
        ));
    });
    describe('element trees and children', function() {
      it('should error reconnecting missing children', () =>
        expectMarkupMismatch(<div><div /></div>, <div />));
      it('should error reconnecting added children', () =>
        expectMarkupMismatch(<div />, <div><div /></div>));
      it('should error reconnecting more children', () =>
        expectMarkupMismatch(<div><div /></div>, <div><div /><div /></div>));
      it('should error reconnecting fewer children', () =>
        expectMarkupMismatch(<div><div /><div /></div>, <div><div /></div>));
      it('should error reconnecting reordered children', () =>
        expectMarkupMismatch(
          <div><div /><span /></div>,
          <div><span /><div /></div>,
        ));
      it('should error reconnecting a div with children separated by whitespace on the client', () =>
        expectMarkupMismatch(
          <div id="parent"><div id="child1" /><div id="child2" /></div>,