This reverts commit b57be748 and
disables the test/mjsunit/debug-clearbreakpointgroup.js because
BreakLocationIterator::ClearBreakPoint is already broken for unrelated reasons (see v8:3924).

BUG=v8:3877
LOG=N
TEST=cctest/test-heap/Regress3877

Review URL: https://codereview.chromium.org/957373002

Cr-Commit-Position: refs/heads/master@{#26893}