Add packages to optimize svgs dynamically

These packages will be used to dynamically optimize SVG images
during the build.

R=jacktfranklin@chromium.org

Bug: 1216402
Change-Id: I04e95aa7d79c9d67beaf8a7861182c52b16b7d0f
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2939992
Reviewed-by: Jack Franklin <jacktfranklin@chromium.org>
Commit-Queue: Tim van der Lippe <tvanderlippe@chromium.org>
diff --git a/node_modules/css-tree/lib/utils/clone.js b/node_modules/css-tree/lib/utils/clone.js
new file mode 100644
index 0000000..927294b
--- /dev/null
+++ b/node_modules/css-tree/lib/utils/clone.js
@@ -0,0 +1,21 @@
+var List = require('../common/List');
+
+module.exports = function clone(node) {
+    var result = {};
+
+    for (var key in node) {
+        var value = node[key];
+
+        if (value) {
+            if (Array.isArray(value) || value instanceof List) {
+                value = value.map(clone);
+            } else if (value.constructor === Object) {
+                value = clone(value);
+            }
+        }
+
+        result[key] = value;
+    }
+
+    return result;
+};