I would like to see a core HTML/CSS/Javascript spec that is a union of features proven to be available and work consistently across all browsers. The spec should incorporate ideas that are obvious in hindsight, such as the DOM diffing optimizations in frameworks like React, or running each tab in its own process.
I think that it should also take a broad perspective approach on things like padding and margin. For example, use simpler abstractions from layout engines like Qt or the layout-as-a-matrix-solver math behind iOS's Auto Layout constraints.
Find the commonalities to give us a high-level abstraction over all the div/span/table concepts of the web, then show a mapping from the abstraction to the quirks of how a div flows, for example. Maybe we could allow one transpiler to go from the solvable/predictable rules to the quirks of say HTML5.
The steps in this process could be relatively tiny and easy to test. It should render the DOM at > 60 fps on a Pentium 100 or equivalent, since games used to do that before they even had OpenGL.
I don't see any step of this process that is intractable. Once we had that, it should be relatively straightforward to build an open source browser as a base spec implementation. This is the sort of thing I fantasized about working on before I got so burned out.
