- Using realloc is still unsafe as the allocator, using array_buffer_allocator
  - Fixing tests to avoid overlapping stores, adding more tests

BUG=v8:5344

R=ahaas@chromium.org, mlippautz@chromium.org

Review-Url: https://codereview.chromium.org/2319983002
Cr-Commit-Position: refs/heads/master@{#39329}