To manage BasicBlock's predecessors and successors we now use plain
std::vector.

The change also moves bunch of method definitions from header files
to implementation files.

In zlib, the change brings 3x improvement in the scheduler's memory
consumption. The --turbo-stats flag says we go 169MB -> 55MB in
the scheduler, 383MB -> 268MB overall.

BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/606403003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24308 ce2b1a6d-e550-0410-aec6-3dcde31c8c00