**Do you want to request a *feature* or report a *bug*?**
*Feature*

**What is the current behavior?**
In Firefox the `dialog` element is not implemented. We use a polyfill to be able to support it. Everything works well. But React warns that the `dialog` element is unrecognized, and this on each page load, which is quite useless (for this specific case).
I would like the possibility to disable the  warning but only for some elements. So the utility of this warning remains when the developer mistype the component name.

**What is the expected behavior?**
Once we specified which tag are "accepted/normal" React will not warn on specified unrecognized tags.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
React 16
Firefox 57

In previous versions there was no warning.

Is this clear enough? Do you need any other information?
Cheers
}
    var testElement = parent.namespaceURI === HTML_NAMESPACE
      ? testDocument.createElement(parent.tagName)
      : testDocument.createElementNS(
          (parent.namespaceURI: any),
          parent.tagName,
        );
    testElement.innerHTML = html;
    return testElement.innerHTML;
  };
}
function ensureListeningTo(rootContainerElement, registrationName) {
  var isDocumentOrFragment =
    rootContainerElement.nodeType === DOCUMENT_NODE ||
    rootContainerElement.nodeType === DOCUMENT_FRAGMENT_NODE;
  var doc = isDocumentOrFragment
    ? rootContainerElement
    : rootContainerElement.ownerDocument;
  listenTo(registrationName, doc);
}
function getOwnerDocumentFromRootContainer(
  rootContainerElement: Element | Document,
): Document {
  return rootContainerElement.nodeType === DOCUMENT_NODE
    ? (rootContainerElement: any)
    : rootContainerElement.ownerDocument;
}
var mediaEvents = {
  topAbort: 'abort',
  topCanPlay: 'canplay',