Add URL filter to trigger punycode for Japanese homographic sequences.

      BUG=37201
TEST=net_unittests.exe --gtest_filter=NetUtilTest.IDNToUnicode*
Review URL: http://codereview.chromium.org/3011012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@53850 0039d316-1c4b-4281-b951-d872f2087c98