[DevTools] Prepare to move Popover to shadow DOM.

third_party/WebKit/Source/devtools/front_end/object_ui/objectPopover.css

+/*
+ * 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.
+ */
+
+.object-popover-title {
+    text-overflow: ellipsis;
+    overflow: hidden;
+    white-space: nowrap;
+    font-weight: bold;
+    padding-left: 18px;
+}
+
+.object-popover-tree {
+    border-top: 1px solid rgb(184, 184, 184);
+    overflow: auto;
+    position: absolute;
+    top: 21px;
+    bottom: 5px;
+    left: 5px;
+    right: 5px;
+    margin-top: 1px;
+}
+
+.object-popover-container {
+    display: inline-block;
+}
+
+.function-popover-title {
+    border-bottom: 1px solid #AAA;
+    margin-bottom: 3px;
+    padding-bottom: 2px;
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+}
+
+.function-popover-title .function-name {
+    font-weight: bold;
+}
+
+.function-title-link-container {
+    display: flex;
+    align-items: center;
+    position: relative;
+    margin-left: 10px;
+}
+
+.function-location-step-into {
+    position: relative;
+    height: 14px;
+    transform: rotate(-90deg);
+}