Bug 1567938 - Fix improper uses of #737373 in preferences. r=jaws

Differential Revision: https://phabricator.services.mozilla.com/D38883

--HG--
extra : moz-landing-system : lando

browser/components/preferences/clearSiteData.css

@@ -15,6 +15,6 @@
 }
 
 .option-description {
-  color: #737373;
+  color: var(--in-content-deemphasized-text);
   margin-top: -0.5em !important;
 }

browser/components/preferences/sitePermissions.css

@@ -29,7 +29,7 @@
 }
 
 #permissionsDisableDescription {
-  color: #737373;
+  color: var(--in-content-deemphasized-text);
   line-height: 110%;
 }
 

browser/themes/shared/incontentprefs/preferences.inc.css

@@ -55,7 +55,7 @@ html|h2 {
 
 description.indent,
 .indent > description {
-  color: #737373;
+  color: var(--in-content-deemphasized-text);
 }
 
 button,