bring in modified copy of klona/json

src/compiler/utils/clone.ts

@@ -0,0 +1,33 @@
+// adapted from klona v2.0.4 - https://github.com/lukeed/klona
+// (c) Luke Edwards, under MIT License
+
+// The sole modification is to skip function values in objects when cloning, so we don't break tests.
+
+export function clone(val) {
+	let k, out, tmp;
+
+	if (Array.isArray(val)) {
+		out = Array(k=val.length);
+		while (k--) out[k] = (tmp=val[k]) && typeof tmp === 'object' ? clone(tmp) : tmp;
+		return out;
+	}
+
+	if (Object.prototype.toString.call(val) === '[object Object]') {
+		out = {}; // null
+		for (k in val) {
+			if (k === '__proto__') {
+				Object.defineProperty(out, k, {
+					value: clone(val[k]),
+					configurable: true,
+					enumerable: true,
+					writable: true
+				});
+			} else if (typeof val[k] !== 'function') { // MODIFICATION: skip functions
+				out[k] = (tmp=val[k]) && typeof tmp === 'object' ? clone(tmp) : tmp;
+			}
+		}
+		return out;
+	}
+
+	return val;
+}