Remove RTT.derivedTypes and all generated initializations thereof.

compiler/lib/implementation/rtt.js

Index: compiler/lib/implementation/rtt.js
diff --git a/compiler/lib/implementation/rtt.js b/compiler/lib/implementation/rtt.js
index 995ce8c8eab5f826da92389654aaf9e8a47e5e88..b1e7450de0537633c19b6070c0bcd23cd1e2583d 100644
--- a/compiler/lib/implementation/rtt.js
+++ b/compiler/lib/implementation/rtt.js
@@ -33,9 +33,6 @@ function RTT(classkey, typekey, typeargs, returnType, functionType, named) {
 /** @type {Object.<string, Object>} */
 RTT.types = {};
 
-/** @type {Array.<RTT>} */
-RTT.prototype.derivedTypes = [];
-
 /** @return {string} */
 RTT.prototype.toString = function() { return this.typeKey; }