[DevTools] Prepare to move Popover to shadow DOM.

third_party/WebKit/Source/devtools/front_end/components/imagePreview.css

Index: third_party/WebKit/Source/devtools/front_end/components/imagePreview.css
diff --git a/third_party/WebKit/Source/devtools/front_end/components/imagePreview.css b/third_party/WebKit/Source/devtools/front_end/components/imagePreview.css
new file mode 100644
index 0000000000000000000000000000000000000000..08020e5bdecd15380d33f80e62cdb54244d64225
--- /dev/null
+++ b/third_party/WebKit/Source/devtools/front_end/components/imagePreview.css
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2017 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.
+ */
+
+.image-preview-container {
+    background: transparent;
+    text-align: center;
+    border-spacing: 0;
+}
+
+.image-preview-container img {
+    margin: 2px auto;
+    max-width: 100px;
+    max-height: 100px;
+    background-image: url(Images/checker.png);
+    -webkit-user-select: text;
+    -webkit-user-drag: auto;
+}
+
+.image-container {
+    padding: 0;
+}