Gallery: Set opacity=1 when printing image.

ui/file_manager/gallery/css/gallery.css

 /* Copyright (c) 2014 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
 body {
   -webkit-user-select: none;
   font-size: 84%;
   margin: 0;
 }
 
@@ skipping 120 matching lines @@
     display: -webkit-box;
   }
 
   /* Do not print the screen resolution image. */
   .gallery .image-container > canvas.image {
     display: none !important;
   }
 
   /* Print the full resolution image instead. */
   .gallery .image-container > canvas.fullres {
-    display: block !important;
     height: auto !important;
     max-height: 100%;
     max-width: 100%;
+    opacity: 1 !important;
     position: static !important;
     transform: none !important;
     visibility: visible !important;
     width: auto !important;
   }
 }
 
 /* Toolbar */
 
 .gallery > .header,
@@ skipping 1206 matching lines @@
   background-color: rgba(255, 0, 0, 0.3);
 }
 
 .debug-me .load-target-external-metadata::before {
   background-color: rgba(0, 255, 0, 0.3);
 }
 
 .debug-me .load-target-file-entry::before {
   background-color: rgba(0, 0, 255, 0.3);
 }