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 - Several "rm" commands are unnecessary because of rsync_exclude.txt.
 - Audited code that was replacing NBSP in polymer-mini.html (added in
   r332329). Seems to have no effect (no diff exists after running
   the command). Removed related TODO for Polymer 2.
 - Remove unused files from third_party/web-animations-js/. These files
   are not included in the build anyway.

Bug: 738611
Change-Id: I372143a9bc1fd3f18d5aa6fb7fe735fdbdb82015
Reviewed-on: https://chromium-review.googlesource.com/c/1338334
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608860}