I was maintaining a port of the Opera browser for Japanese feature phones in 2007. We supported flash in 11Mb of RAM: 6 for the browser, 5 for flash. That included the screen buffer IIRC. We ran regular desktop web sites under these conditions just fine (with 2007 expectations regarding interop). The experience may not have been great, but that was much more an issue of tiny screens without touch support than anything else. Had Apple wanted to, they would absolutely have been able to support flash on the iPhone. We could on much worse hardware. Not doing so was about controlling the platform, not about technical limitations.

http://www.operasoftware.com/press/releases/mobile/opera-del...