Port b994ad45

Original commit message:
Also factor out test cases from test-run-machops.cc into test-run-load-store.cc

TEST=cctest/test-run-load-store/RunLoadStoreZeroExtend64, cctest/test-run-load-store/RunOobCheckedLoadT_pseudo7, cctest/test-run-load-store/RunOobCheckedLoad_pseudo7
BUG=chromium:599717
LOG=Y

Review-Url: https://codereview.chromium.org/1907363002
Cr-Commit-Position: refs/heads/master@{#36017}