Link to “Intent to Deprecate” thread
Remove the SVGZoomEvent interface and the corresponding onzoom attribute.
SVGZoomEvent doesn't work at all in Blink. It can be created and hooked up using onzoom="..." but it is never fired by the browser.
It has been removed from the SVG 2.0 specification:
The interface has been around in WebKit and Blink for a long time. Originates in:
Usage information from UseCounter