Fix duplicate x icon (cancel) on active search field.

Fixes #1136.
// FREEBIE

stylesheets/_index.scss

@@ -147,8 +147,6 @@ input.search {
     display: block;
     width: $search-x-size;
     height: $search-x-size;
-    background: url('/images/x.svg') no-repeat center;
-    background-size: cover;
   }
 
   &::-webkit-search-cancel-button:hover {

stylesheets/android-dark.scss

@@ -112,10 +112,6 @@ $text-dark: #CCCCCC;
     background-color: $grey-dark_l3;
     border-color: $grey-dark_l2;
     @include invert-text-color;
-    &::-webkit-search-cancel-button {
-      background: url('/images/x_white.svg') no-repeat center;
-      background-size: cover;
-    }
     &.active.ltr, &.active.rtl {
       background-image: url('/images/x_white.svg');
     }

stylesheets/manifest.css

@@ -855,9 +855,7 @@ input.search {
     -webkit-appearance: none;
     display: block;
     width: 16px;
-    height: 16px;
-    background: url("/images/x.svg") no-repeat center;
-    background-size: cover; }
+    height: 16px; }
   input.search::-webkit-search-cancel-button:hover {
     cursor: pointer; }
 
@@ -2004,9 +2002,6 @@ li.entry .error-icon-container {
     .android-dark .search::selection {
       background: white;
       color: #454545; }
-    .android-dark .search::-webkit-search-cancel-button {
-      background: url("/images/x_white.svg") no-repeat center;
-      background-size: cover; }
     .android-dark .search.active.ltr, .android-dark .search.active.rtl {
       background-image: url("/images/x_white.svg"); }
   .android-dark .bubble {