Port 5912e0f0

Original commit message:
    Add StringLessThanStub, StringLessThanOrEqualStub, StringGreaterThanStub
    and StringGreaterThanOrEqualStub, based on the CodeStubAssembler, and
    hook them up with TurboFan (and Ignition). The stubs are currently
    essentially comparable with the StringCompareStub, which is now
    obsolete. We can later extend these stubs to cover more interesting
    cases (i.e. two byte sequential string comparisons, etc.).

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1761403002

Cr-Commit-Position: refs/heads/master@{#34508}