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/usage.js b/node_modules/csso/lib/usage.js
new file mode 100644
index 0000000..40b3ddb
--- /dev/null
+++ b/node_modules/csso/lib/usage.js
@@ -0,0 +1,79 @@
+var hasOwnProperty = Object.prototype.hasOwnProperty;
+
+function buildMap(list, caseInsensitive) {
+    var map = Object.create(null);
+
+    if (!Array.isArray(list)) {
+        return null;
+    }
+
+    for (var i = 0; i < list.length; i++) {
+        var name = list[i];
+
+        if (caseInsensitive) {
+            name = name.toLowerCase();
+        }
+
+        map[name] = true;
+    }
+
+    return map;
+}
+
+function buildList(data) {
+    if (!data) {
+        return null;
+    }
+
+    var tags = buildMap(data.tags, true);
+    var ids = buildMap(data.ids);
+    var classes = buildMap(data.classes);
+
+    if (tags === null &&
+        ids === null &&
+        classes === null) {
+        return null;
+    }
+
+    return {
+        tags: tags,
+        ids: ids,
+        classes: classes
+    };
+}
+
+function buildIndex(data) {
+    var scopes = false;
+
+    if (data.scopes && Array.isArray(data.scopes)) {
+        scopes = Object.create(null);
+
+        for (var i = 0; i < data.scopes.length; i++) {
+            var list = data.scopes[i];
+
+            if (!list || !Array.isArray(list)) {
+                throw new Error('Wrong usage format');
+            }
+
+            for (var j = 0; j < list.length; j++) {
+                var name = list[j];
+
+                if (hasOwnProperty.call(scopes, name)) {
+                    throw new Error('Class can\'t be used for several scopes: ' + name);
+                }
+
+                scopes[name] = i + 1;
+            }
+        }
+    }
+
+    return {
+        whitelist: buildList(data),
+        blacklist: buildList(data.blacklist),
+        scopes: scopes
+    };
+}
+
+module.exports = {
+    buildIndex: buildIndex
+};