Issue #2181487 by sqndr: Update search icon to svg.

core/misc/icons/424242/loupe.svg

+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16"><path fill="#424242" d="M14.648 12.788l-4.23-4.228c.525-.855.834-1.858.834-2.938 0-3.105-2.52-5.624-5.627-5.624-3.106.002-5.625 2.521-5.625 5.627 0 3.105 2.519 5.625 5.625 5.625 1.076 0 2.08-.309 2.936-.832l4.229 4.229c.194.195.515.195.707 0l1.151-1.146c.194-.2.194-.519 0-.713zm-13.35-7.163c0-2.39 1.938-4.327 4.327-4.327 2.391 0 4.328 1.937 4.328 4.327 0 2.391-1.936 4.327-4.328 4.327-2.39 0-4.327-1.936-4.327-4.327z"/></svg>

core/misc/icons/505050/loupe.svg

+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16"><path fill="#505050" d="M14.648 12.788l-4.23-4.228c.525-.855.834-1.858.834-2.938 0-3.105-2.52-5.624-5.627-5.624-3.106.002-5.625 2.521-5.625 5.627 0 3.105 2.519 5.625 5.625 5.625 1.076 0 2.08-.309 2.936-.832l4.229 4.229c.194.195.515.195.707 0l1.151-1.146c.194-.2.194-.519 0-.713zm-13.35-7.163c0-2.39 1.938-4.327 4.327-4.327 2.391 0 4.328 1.937 4.328 4.327 0 2.391-1.936 4.327-4.328 4.327-2.39 0-4.327-1.936-4.327-4.327z"/></svg>

core/themes/bartik/css/style.css

@@ -1582,14 +1582,25 @@ div.password-suggestions {
   cursor: pointer;
   text-indent: -9999px;
   border-color: #e4e4e4 #d2d2d2 #b4b4b4;
-  background: url(../images/search-button.png) no-repeat center top;
+  background: #f0f0f0 url("../../../misc/icons/505050/loupe.svg") no-repeat center;
   overflow: hidden;
 }
 #search-block-form input.form-submit:hover,
 #search-block-form input.form-submit:focus,
 #search-form input.form-submit:hover,
 #search-form input.form-submit:focus {
-  background-position: center bottom;
+  background: #dedede url("../../../misc/icons/424242/loupe.svg") no-repeat center;
+}
+.no-svg #search-block-form input.form-submit,
+.no-svg #search-form input.form-submit {
+  background: #f0f0f0 url("../../../misc/icons/505050/loupe.png") no-repeat center;
+}
+.no-svg #search-block-form input.form-submit:hover,
+.no-svg #search-block-form input.form-submit:focus,
+.no-svg #search-form input.form-submit:hover,
+.no-svg #search-form input.form-submit:focus {
+  background: #dedede url("../../../misc/icons/424242/loupe.png") no-repeat center;
+
 }
 #search-form .form-item-keys label {
   display: block;