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. 
expect(e.getAttribute('data-foobar')).toBe('true');
      });
      itRenders('unknown data- attributes with boolean false', async render => {
        const e = await render(<div data-foobar={false} />);
        expect(e.getAttribute('data-foobar')).toBe('false');
      });
      itRenders(
        'no unknown data- attributes with casing and null value',
        async render => {
          const e = await render(<div data-fooBar={null} />, 1);
          expect(e.hasAttribute('data-foobar')).toBe(false);
        },
      );
      itRenders('custom attributes for non-standard elements', async render => {
        const e = await render(<nonstandard foo="bar" />);
        expect(e.getAttribute('foo')).toBe('bar');
      });
      itRenders('unknown attributes for custom elements', async render => {
        const e = await render(<custom-element foo="bar" />);
        expect(e.getAttribute('foo')).toBe('bar');
      });
      itRenders(
        'no unknown attributes for custom elements with null value',
        async render => {
          const e = await render(<custom-element foo={null} />);
          expect(e.hasAttribute('foo')).toBe(false);
        },
      );
      itRenders(
        'unknown attributes for custom elements using is',