Disable preload for module scripts

This patch disables preload for <script type="module">, to prevent
duplicated requests due to credentials mode mismatch. In the long term,
we should teach Preload Scanner about the module script credentials mode
and re-enable preload.

BUG=717525

Review-Url: https://codereview.chromium.org/2871153002
Cr-Commit-Position: refs/heads/master@{#470853}
1 file changed