Patched some very obscure bugs

test/scripts/polyfill-insert.toy

@@ -0,0 +1,22 @@
+//polyfill the _insert function
+fn _insert(self, k, v) {
+	var tmp1 = v;
+	var tmp2;
+	for (var i = k; i < self.length(); i++) {
+		tmp2 = self[i];
+		self[i] = tmp1;
+		tmp1 = tmp2;
+	}
+
+	self.push(tmp1);
+	return self;
+}
+
+var a = [1, 2, 3];
+
+a = a.insert(1, 42);
+
+assert a == [1, 42, 2, 3], "polyfill insert failed";
+
+
+print "All good";