[invalidations] Convert invalidations to use TreeOutline

Source/devtools/front_end/timeline/invalidationsTree.css

+/*
+ * Copyright 2015 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.
+ */
+
+.header, .children, .content {
+    min-height: initial;
+    line-height: initial;
+}
+
+.children li::before {

[pfeldman, 2015/04/09 10:15:52]

So you are making it always expanded? I guess we should enrich treeoutline with
this capability. Mind inserting a FIXME here?

[pdr., 2015/04/09 18:20:34]

Yep! Done. crbug.com/475618 is tracking this. Should be pretty easy to
implement.

+    display: none;
+}
+
+.content {
+    margin-bottom: 4px;
+}
+
+.content .stack-preview-container {
+    margin-left: 8px;
+}
+
+.content .node-list {
+    margin-left: 10px;
+}