Add @webref/idl dependency

Signed-off-by: Victor Porof <victorporof@chromium.org>
Bug: 1325812
Change-Id: I044170880d20ce0402062755787cccafd63c6a42
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3695370
Reviewed-by: Mathias Bynens <mathias@chromium.org>
diff --git a/node_modules/@webref/idl/css-properties-values-api.idl b/node_modules/@webref/idl/css-properties-values-api.idl
new file mode 100644
index 0000000..eb7d7b0
--- /dev/null
+++ b/node_modules/@webref/idl/css-properties-values-api.idl
@@ -0,0 +1,23 @@
+// GENERATED CONTENT - DO NOT EDIT
+// Content was automatically extracted by Reffy into webref
+// (https://github.com/w3c/webref)
+// Source: CSS Properties and Values API Level 1 (https://drafts.css-houdini.org/css-properties-values-api-1/)
+
+dictionary PropertyDefinition {
+  required DOMString name;
+           DOMString syntax       = "*";
+  required boolean   inherits;
+           DOMString initialValue;
+};
+
+partial namespace CSS {
+  undefined registerProperty(PropertyDefinition definition);
+};
+
+[Exposed=Window]
+interface CSSPropertyRule : CSSRule {
+    readonly attribute CSSOMString name;
+    readonly attribute CSSOMString syntax;
+    readonly attribute boolean inherits;
+    readonly attribute CSSOMString? initialValue;
+};