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('width')).toBe('30');
      });
      itRenders('simple strings', async render => {
        const e = await render(<div width={'30'} />);
        expect(e.getAttribute('width')).toBe('30');
      });
      itRenders('no string prop with true value', async render => {
        const e = await render(<a href={true} />, 1);
        expect(e.hasAttribute('href')).toBe(false);
      });
      itRenders('no string prop with false value', async render => {
        const e = await render(<a href={false} />, 1);
        expect(e.hasAttribute('href')).toBe(false);
      });
      itRenders('no string prop with null value', async render => {
        const e = await render(<div width={null} />);
        expect(e.hasAttribute('width')).toBe(false);
      });
    });
    describe('boolean properties', function() {
      itRenders('boolean prop with true value', async render => {
        const e = await render(<div hidden={true} />);
        expect(e.getAttribute('hidden')).toBe('');
      });
      itRenders('boolean prop with false value', async render => {
        const e = await render(<div hidden={false} />);
        expect(e.getAttribute('hidden')).toBe(null);
      });
      itRenders('boolean prop with self value', async render => {
        const e = await render(<div hidden="hidden" />);