MD Settings: consolidate .no-outline css rules.

chrome/browser/resources/settings/settings_shared_css.html

 <link rel="import" href="chrome://resources/cr_elements/shared_style_css.html">
 <link rel="import" href="settings_vars_css.html">
 
 <!-- Common styles for Material Design settings. -->
 <dom-module id="settings-shared">
   <template>
     <style include="cr-shared-style">
       /* Included here so we don't have to include "iron-positioning" in every
        * stylesheet. See crbug.com/498405. */
       [hidden] {
@@ skipping 285 matching lines @@
       .settings-box .start.two-line {
         display: flex;
       }
 
       /* The start (left in LTR) part (horizontally) of a row. */
       .settings-box .start {
         align-items: center;
         flex: auto;
       }
 
+      .no-outline,
       [scrollable] .no-outline {

[dpapad, 2017/04/03 23:45:50]

Isn't "[scrollable] .no-outline" redundant here?

[scottchen, 2017/04/04 17:44:24]

There are other "[scrollable] .something" rules that are considered more
specific than .no-outline, so this is necessary to override those.

         background: none;
         outline: none;
-        cursor: initial;
       }
 
       /* The secondary-action wraps a clickable sub-area of a .settings-box.
        * An example is the |sign out| button on the People settings.
        * Here is an example with and without a secondary action box:
        *
        *  +-------------------------------------------------------+
        *  | Main action area .settings-box    | .secondary-action |
        *  +-------------------------------------------------------+
        *  | Another setting-box without a secondary-action        |
@@ skipping 62 matching lines @@
         transform: rotate(-135deg);
       }
 
       .column-header {
         color: var(--paper-grey-600);
         font-weight: 500;
       }
     </style>
   </template>
 </dom-module>