queryCommandState should consider the nested list

When we run queryCommandState on the nested list,
it only finds the parent list so the nested list is not
considered. This CL allows the command to find the
nested list on the selection.

BUG=385374
TEST=editing/execCommand/queryCommandState-list.html

Review-Url: https://codereview.chromium.org/2268843002
Cr-Commit-Position: refs/heads/master@{#413764}
2 files changed