<input type=file webkitdirectory>: Launch picker on Enter keyup

Avoid key repeat triggering an unintentional commit of the subsequent
dialog by launching the picker on the Enter keyup event rather than on
keydown.

Bug: 637098
Change-Id: Ia327a7a9f92c34fd3fcdf971d8c21a5ce744254b
Reviewed-on: https://chromium-review.googlesource.com/814916
Commit-Queue: Joshua Bell <jsbell@chromium.org>
Reviewed-by: Chris Palmer <palmer@chromium.org>
Reviewed-by: Emily Stark <estark@chromium.org>
Reviewed-by: Keishi Hattori <keishi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#523507}
9 files changed