Change IME indicator character from U+9177 to U+6CE8

BUG=286623
TEST=None

Review URL: https://codereview.chromium.org/25737006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230428 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230428