Add function to retrieve all property descriptors

This is essentially a recursive form of Object.getOwnPropertyDescriptors
which ignores Symbol-keyed properties. Intended for debugging only; this
function is far from performant.

lib/objects.js

@@ -75,6 +75,36 @@ function alphabetiseProperties(input, strictCase = false){
 }
 
 
+/**
+ * Retrieve a descriptor for each property available on an object.
+ *
+ * Both inherited and non-enumerable properties are included.
+ * The usual rules of prototypal inheritance apply; redefined
+ * properties replace their inherited counterparts.
+ *
+ * @param {Object} subject
+ * @return {Map} A list of property descriptors keyed by name.
+ * @example getProperties(foo) == Map{"keys" => descriptors}
+ */
+function getProperties(subject){
+	let object = subject;
+	const refs = new WeakSet();
+	const ancestry = [subject];
+	while((object = Object.getPrototypeOf(object)) && !refs.has(object))
+		ancestry.push(object);
+
+	const result = new Map();
+	for(const obj of ancestry.reverse()){
+		const names = Object.getOwnPropertyNames(obj);
+		for(const name of names){
+			const desc = Object.getOwnPropertyDescriptor(obj, name);
+			result.set(name, desc);
+		}
+	}
+
+	return result;
+}
+
 
 /**
  * "Flatten" a (possibly nested) list of strings into a single-level array.