Fix Tooltip positioning issue with SVG targets

[raymondcao-everlaw]

Defect Fixes

Addresses #2406.

The issue was that if the target of a global tooltip was an SVG, the tooltip would not be positioned next to the target when triggered (it will often appear offscreen). The source of the problem was that DomHandler.getOuterWidth and DomHandler.getOuterHeight rely on Element.offsetWidth to get the target element's width. This works for HTMLElement instances but not SVGElement instances.

My PR uses Element.getBoundingClientRect to get the target element's width when Element.offsetWidth is undefined.

[mertsincan]

Thanks a lot for your contribution!

Best Regards,