Move it to HARMONY_STAGED from HARMONY_INPROGRESS.

Update test262.status now that case mapping tests are passing with
'--harmony' specified.

BUG=v8:4476,v8:4477
LOG=Y
TEST=test262/{built-ins,intl402}/Strings/*, webkit/fast/js/*,
     mjsunit/string-case, intl/general/case*
CQ_INCLUDE_TRYBOTS=tryserver.v8:v8_linux_noi18n_rel_ng

Review-Url: https://codereview.chromium.org/1990083002
Cr-Commit-Position: refs/heads/master@{#36379}