[ES6 modules] Log to console if module script load failed due to invalid MIME type.

Before this CL, module script load of invalid mime type has silently failed.
This CL aims to help web developer by notifying this tricky failure to DevTools console.

Bug: 594639
Change-Id: I9533fdb325fcecccedbf24b9819e65f116a17c11
Reviewed-on: https://chromium-review.googlesource.com/566746
Commit-Queue: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Hiroshige Hayashizaki <hiroshige@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486331}
5 files changed