We missed this because Flow wasn't being run properly on Travis but now that it is, it's clear that #7716 introduced a bunch of new Flow failures. Most of these shouldn't be too bad and I like to say "you break it you buy it" so this one is for you @Aweary :)

There were a couple other pre-existing Flow issues that @vjeux is going to fix, so mostly this should just be the TestRenderer issues.

namespaceURI = hostContainerInfo._namespaceURI;
      parentTag = hostContainerInfo._tag;
    }
    if (namespaceURI == null ||
        namespaceURI === DOMNamespaces.svg && parentTag === 'foreignobject') {
      namespaceURI = DOMNamespaces.html;
    }
    if (namespaceURI === DOMNamespaces.html) {
      if (this._tag === 'svg') {
        namespaceURI = DOMNamespaces.svg;
      } else if (this._tag === 'math') {
        namespaceURI = DOMNamespaces.mathml;
      }
    }
    this._namespaceURI = namespaceURI;
    if (__DEV__) {
      var parentInfo;
      if (hostParent != null) {
        parentInfo = hostParent._ancestorInfo;
      } else if (hostContainerInfo._tag) {
        parentInfo = hostContainerInfo._ancestorInfo;
      }
      if (parentInfo) {
        
        
        validateDOMNesting(this._tag, null, this, parentInfo);
      }
      this._ancestorInfo =
        validateDOMNesting.updatedAncestorInfo(parentInfo, this._tag, this);
    }