Who and why have changed layout of formulas? Now I can't see formulas in my browser Opera 9.27 [http://opera-usb.com/download/opera927int.zip] https://s.sender.mobi/u/image/2016/6/11/bvB7Yijef/-.JPG . Yes, it's old but my computer has not enough resources for newer browser. Please explain what gain gives new layout and what was purpose.
It sounds like the PNG fall-back is not loaded properly. One possibly is that this Opera version claims to support SVG (by returning true for document.implementation.hasFeature('http://www.w3.org/TR/SVG11/feature#Image', '1.1')), but does not implement it well enough yet.
If this turns out to be the case, we might be able to fix the user experience by changing the test to trigger PNG fall-back rendering for this browser.
See also this related task: T136905: MathML/SVG/PNG mode causing problems with Nook Tablet.