Port d412cfa2

Original commit message:
    [Atomics] Remove Atomics code stubs; use TF ops

    Reland of (https://codereview.chromium.org/1891033002)

    This is a much cleaner solution, which won't require nearly as much
    architecture-specific code. Thanks bmeurer@!

R=binji@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=v8:4614
LOG=N

Review URL: https://codereview.chromium.org/1899033002

Cr-Commit-Position: refs/heads/master@{#35631}