- Move usable functions into proper heap-utils.h/.cc files and remove
  utils-inl.h file
- Fix assumptions accross the board relying on certain behavior that is not
  invariant

This is a requirement for modifying page size.

BUG=chromium:581412
LOG=N
R=ulan@chromium.org

Review-Url: https://codereview.chromium.org/1999753002
Cr-Commit-Position: refs/heads/master@{#36410}