Check CORS policy on redirect in TextTrackLoader

BUG=633885
TEST=new case in http/tests/security/text-track-crossorigin.html

Review-Url: https://codereview.chromium.org/2367583002
Cr-Commit-Position: refs/heads/master@{#421919}
void TextTrackLoader::cancelLoad()
{
     clearResource();
 }

void TextTrackLoader::cancelLoad()
{
     clearResource();
 }
