GitLab

 - Move some styles from shared_style_css.html to paper_button_style_css.html.
 - Update paper-button styles per latest spec.
 - Collapse previously different types of buttons "primary" and "action" into a
   single button type.

Note this change is intentionally changing the shared styling for buttons. If a
certain WebUI page needs a different pre-MD refresh style, should be updated
individually to override (hopefully there are no such cases though).

Bug: 832173
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: If083bf3ad1d60623300bb9e584ae9179e815ef7d
Reviewed-on: https://chromium-review.googlesource.com/1028478Reviewed-by: Scott Chen <scottchen@chromium.org>
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553689}