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/csso/lib/replace/Atrule.js b/node_modules/csso/lib/replace/Atrule.js
new file mode 100644
index 0000000..b64245c
--- /dev/null
+++ b/node_modules/csso/lib/replace/Atrule.js
@@ -0,0 +1,9 @@
+var resolveKeyword = require('css-tree').keyword;
+var compressKeyframes = require('./atrule/keyframes');
+
+module.exports = function(node) {
+    // compress @keyframe selectors
+    if (resolveKeyword(node.name).basename === 'keyframes') {
+        compressKeyframes(node);
+    }
+};