Remove redundant icon.

packages/theme-dark-extension/style/icons/md/search-white.svg

@@ -1,7 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 18 18">
-    <path fill="#FFFFFE" d="M12.1,10.9h-0.7l-0.2-0.2c0.8-0.9,1.3-2.2,1.3-3.5c0-3-2.4-5.4-5.4-5.4S1.8,4.2,1.8,7.1s2.4,5.4,5.4,5.4
-        c1.3,0,2.5-0.5,3.5-1.3l0.2,0.2v0.7l4.1,4.1l1.2-1.2L12.1,10.9z M7.1,10.9c-2.1,0-3.7-1.7-3.7-3.7s1.7-3.7,3.7-3.7s3.7,1.7,3.7,3.7
-        S9.2,10.9,7.1,10.9z"/>
-    <path fill="none" d="M0,0h18v18H0V0z"/>
-</svg>

packages/theme-dark-extension/style/urls.css

@@ -62,7 +62,7 @@
   --jp-icon-inverse-circle: url('icons/md/circle-inverse.svg');
   --jp-icon-close-circle: url('icons/md/close-circle.svg');
   --jp-icon-inverse-close-circle: url('icons/md/close-circle-inverse.svg');
-  --jp-icon-search: url('icons/md/search-white.svg');
+  --jp-icon-search: url('icons/md/search.svg');
   --jp-icon-search-white: url('icons/md/search.svg');
   --jp-icon-copy: url('icons/md/copy.svg');
   --jp-icon-cut: url('icons/md/cut.svg');