Settings UI: Fix textarea background regression

Since we no longer set a background on the #input in cr_input_style_css
and settings-textarea doesn't have an #inner-input-container element,
add the background to the #input-container.

Bug: 954876
Change-Id: Iaa570c1c8be233043bf70fc56ce179951b8e92d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1578590
Reviewed-by: Dan Beam <dbeam@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653691}
1 file changed