**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`
): HostContext {
    if (__DEV__) {
      const parentHostContextDev = ((parentHostContext: any): HostContextDev);
      const namespace = getChildNamespace(parentHostContextDev.namespace, type);
      const ancestorInfo = updatedAncestorInfo(
        parentHostContextDev.ancestorInfo,
        type,
        null,
      );
      return {namespace, ancestorInfo};
    }
    const parentNamespace = ((parentHostContext: any): HostContextProd);
    return getChildNamespace(parentNamespace, type);
  },
  getPublicInstance(instance) {
    return instance;
  },
  prepareForCommit(): void {
    eventsEnabled = ReactBrowserEventEmitter.isEnabled();
    selectionInformation = ReactInputSelection.getSelectionInformation();
    ReactBrowserEventEmitter.setEnabled(false);
  },
  resetAfterCommit(): void {
    ReactInputSelection.restoreSelection(selectionInformation);
    selectionInformation = null;
    ReactBrowserEventEmitter.setEnabled(eventsEnabled);
    eventsEnabled = null;
  },
  createInstance(
    type: string,