See the original report in https://github.com/facebook/react/issues/10772#issuecomment-333242375.

The problem is that SVG is case sensitive, and so naïvely setting `tabIndex` and relying on insensitivity won't work with it.

The good news is it seems like `tabindex` is the only valid [SVG attribute](https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute) with this problem. We just missed it because it applies both to HTML and SVG.

I think the fix is to add it back to the whitelist. 
scoped: HAS_BOOLEAN_VALUE,
    seamless: HAS_BOOLEAN_VALUE,
    selected: MUST_USE_PROPERTY | HAS_BOOLEAN_VALUE,
    size: HAS_POSITIVE_NUMERIC_VALUE,
    start: HAS_NUMERIC_VALUE,
    
    span: HAS_POSITIVE_NUMERIC_VALUE,
    spellCheck: HAS_STRING_BOOLEAN_VALUE,
    
    
    style: 0,
    
    
    itemScope: HAS_BOOLEAN_VALUE,
    
    
    acceptCharset: 0,
    className: 0,
    htmlFor: 0,
    httpEquiv: 0,
    
    
    value: HAS_STRING_BOOLEAN_VALUE,
  },
  DOMAttributeNames: {
    acceptCharset: 'accept-charset',
    className: 'class',
    htmlFor: 'for',
    httpEquiv: 'http-equiv',
  },