use color swatches for selected bg and fg in svg assets

common/gnome-shell/3.18/dark-assets/switch/switch-on.svg

@@ -2,11 +2,13 @@
 <!-- Created with Inkscape (http://www.inkscape.org/) -->
 
 <svg
+   xmlns:osb="http://www.openswatchbook.org/uri/2009/osb"
    xmlns:dc="http://purl.org/dc/elements/1.1/"
    xmlns:cc="http://creativecommons.org/ns#"
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:svg="http://www.w3.org/2000/svg"
    xmlns="http://www.w3.org/2000/svg"
+   xmlns:xlink="http://www.w3.org/1999/xlink"
    xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
    xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
    width="50"
@@ -17,6 +19,14 @@
    sodipodi:docname="switch-on.svg">
   <defs
      id="defs7541">
+    <linearGradient
+       id="selected_bg_color"
+       osb:paint="solid">
+      <stop
+         style="stop-color:#5294e2;stop-opacity:1;"
+         offset="0"
+         id="stop4166" />
+    </linearGradient>
     <linearGradient
        id="linearGradient4695-1-4-3-5-0-6">
       <stop
@@ -91,6 +101,15 @@
          offset="1"
          style="stop-color:#ffffff;stop-opacity:1;" />
     </linearGradient>
+    <linearGradient
+       inkscape:collect="always"
+       xlink:href="#selected_bg_color"
+       id="linearGradient4168"
+       x1="26"
+       y1="1031.3622"
+       x2="26"
+       y2="1051.3622"
+       gradientUnits="userSpaceOnUse" />
   </defs>
   <sodipodi:namedview
      id="base"
@@ -100,8 +119,8 @@
      inkscape:pageopacity="0.0"
      inkscape:pageshadow="2"
      inkscape:zoom="11.666667"
-     inkscape:cx="26.273653"
-     inkscape:cy="16.301439"
+     inkscape:cx="10.930796"
+     inkscape:cy="16.13001"
      inkscape:current-layer="layer1"
      showgrid="true"
      inkscape:grid-bbox="true"
@@ -140,7 +159,7 @@
         <dc:format>image/svg+xml</dc:format>
         <dc:type
            rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
-        <dc:title></dc:title>
+        <dc:title />
       </cc:Work>
     </rdf:RDF>
   </metadata>
@@ -175,7 +194,7 @@
                x="0"
                y="1029.3622" />
             <rect
-               style="fill:#5294e2;fill-opacity:1;fill-rule:nonzero;stroke:none"
+               style="fill:url(#linearGradient4168);fill-opacity:1;fill-rule:nonzero;stroke:none"
                id="rect2987-0-8-7"
                width="50"
                height="20"