Nah, it's tile-based
concurrent precompositing, like web browsers do. Each tile knows what's in it (i.e. what set of DOM elements); and subscribes to state-change events for those DOM elements; and any such state-change event will trigger the tile to re-render its cached texture. Then, on each frame, all you have to do to draw everything, is to grab the latest cached texture from each tile, and blit those (or set them up as a grid of flat-projected rects in screen-space, if you're in 3D-semantics land.)
You can get additional benefits from this approach, by doing multiple layers of it (e.g. having scrollable surfaces have their own tiles that precompute the inner-document-viewport-space rather than the outer-viewport-space, such that the inner tiles aren't invalidated by scrolling the outer viewport.) This technique ends up forming a tree of tiles, where tiles higher up the tree, when invalidated, re-render trivially by compositing tiles further down the tree into themselves. Thus, another name for this approach is a "precompositing tree."
The difference between this approach and dirty rects, is in the direction of information flow. In tile-based precompositing, the information only flows in one direction—from the user, through view-controller, into the DOM, to the tiles, and then out the display. Dirty rects, meanwhile, are a signal sent backwards, from the display system to the program, essentially telling it that the display system lost/discarded the information needed to re-draw an area, so could the program please send it over again. (The program doesn't even have to re-render in response; some dirty-rects implementations, like X11's DAMAGE extension, just involve the client application re-transmitting pixbuf data to the server from its own precomposited buffer.)
Also, dirty rects / screen-damage doesn't solve the problem of hardware not being fast enough; it solves the problem of hardware not having enough VRAM to do per-frame compositing from undamaged intermediates. In low-VRAM conditions, you can only keep around the final pre-composited image; and so any time you "damage" / make "dirty" a region of the screen (e.g. by removing an overdrawn element, which should have the semantics of revealing whatever was there before that element overdrew it) then you need to propagate a request back to the renderer to re-draw (and, for efficiency, re-draw just that region), because you don't just have an intermediate texture laying around for that window/stage-layer/etc. to re-source it from. If you did, then dirty-rects would never come into play, since you'd just re-composite everything each frame. (Which is cheap even on old-school CPU-only blitters—you just have to alternate which pixmap pointer you're basing your LOADs off of using either a rect-overlap check, or a mask-bitmap [which gets you 8 pixels' mask-states per LOAD.] Even the Gameboy can do it!)