No: this doesn't make sense :/. The core problem is that stuff sits around executing some tiny input handler or animation in a loop, burning CPU. When I have tracked the tabs that are the worst performers down to the code causing a problem, it is never a large amount of code: it is some stupid mechanism that polls the position of something (like the cursor or the scrollbar), or is trying to push some analytics to a server.
This really has nothing to do with the amount of code being downloaded. I realize some people care complain about how much stuff they have to download, but that just isn't what is actually causing most people problems. Sure, tracking CPU is sort of annoying, but it absolutely isn't hard. Chrome already is running these things in separate processes (for security), and the operating system is tracking the time used for each thread: you can just ask it and make some kind of limit if that is what you care about.
I mean, in this article I see ideas for size limits for images, which is at least consistent... but that is going way way too far: 1MB just isn't good enough for a reasonable image. If you care so much about bandwidth, make a bandwidth cap for the page and if it exceeds it--across all media--figure out some way of blocking or punishing the site.
What most of us care about is that there seems to be no limit on the CPU usage of any given page. This is easy to fix--it is a virtual machine, after all!--by just doing the same trick Erlang uses for compiling a preemptive fiber and then limiting its time execution slices.
What I know I care a lot about is when a tab I haven't looked at in three days is suddenly using CPU time _at all_. Just make it so background tabs get severely limited in their ability to do background execution and eventually get stopped entirely, and the problem is essentially solved.
(Chrome, which is apparently already big on these size limits, doesn't do this, and I swear it is because it is against Google's interests to do it as it mostly makes it more difficult to do stuff like tracking and advertising :/.)