Well, sure, but then it couldn't do things like allocate memory, spawn threads, access the network, or draw images on the display--in other words, a pretty useless web browser (but perhaps still better than the Amiga's current choices). ;-)
The current WebKit source, including all tests, is over 200,000 files. I haven't looked at the OWB source, though, so I don't know how much of it was used.
Anyhow, if was as simple as running make, someone would have done it years ago.
Perhaps the maintainer of OWB and the dude working on "Traveller" will put their heads together and come up with something that compiles and runs on all Amiga-like operating systems. It's doubtful, but you never know. The lack of a universal GUI toolkit makes it less than enticing, I'm sure.
EDIT: And in case you didn't catch that, the "glue" is the bit that connects the portable code to the system-specific code. A library like ixemul is a good example, but really anything that translates a generic call like "create_thread" into something like AddTask or CreateProc qualifies as glue. In general, it's a term used to describe any component or logic that connects two or more disparate components.