Backport a small CSS cleanup with .file-container and .file.
Backport a small CSS cleanup with .file-container and .file.

In 0105e3f on master, the '.file-container .file { .. }' rule was split
into '.file-container { .file { .. } }'. This change backports this to
release-2.0.x, in order to help with some upcoming changes and merging
of those changes.

1tush/reviewboard,custode/reviewboard,chipx86/reviewboard,reviewboard/reviewboard,davidt/reviewboard,bkochendorfer/reviewboard,bkochendorfer/reviewboard,KnowNo/reviewboard,1tush/reviewboard,bkochendorfer/reviewboard,custode/reviewboard,brennie/reviewboard,1tush/reviewboard,custode/reviewboard,KnowNo/reviewboard,KnowNo/reviewboard,reviewboard/reviewboard,KnowNo/reviewboard,chipx86/reviewboard,beol/reviewboard,brennie/reviewboard,davidt/reviewboard,beol/reviewboard,1tush/reviewboard,1tush/reviewboard,chipx86/reviewboard,sgallagher/reviewboard,brennie/reviewboard,1tush/reviewboard,brennie/reviewboard,1tush/reviewboard,bkochendorfer/reviewboard,sgallagher/reviewboard,sgallagher/reviewboard,davidt/reviewboard,beol/reviewboard,reviewboard/reviewboard,custode/reviewboard,reviewboard/reviewboard,davidt/reviewboard,1tush/reviewboard,1tush/reviewboard,sgallagher/reviewboard,beol/reviewboard,chipx86/reviewboard