I added ContextFactory.createClassLoader that is called from Context.createClassLoader to remove the need to subclass Context if a custom ClassLoader is required.

js/rhino/src/org/mozilla/javascript/Context.java

@@ -2179,9 +2179,15 @@ public class Context
         f.observeInstructionCount(this, instructionCount);
     }
 
+    /**
+     * Create class loader for generated classes.
+     * The method calls {@link ContextFactory#createClassLoader(ClassLoader)}
+     * using the result of {@link #getFactory()}.
+     */
     public GeneratedClassLoader createClassLoader(ClassLoader parent)
     {
-        return new DefiningClassLoader(parent);
+        ContextFactory f = getFactory();
+        return f.createClassLoader(parent);
     }
 
     public final ClassLoader getApplicationClassLoader()

js/rhino/src/org/mozilla/javascript/ContextFactory.java

@@ -273,6 +273,20 @@ public class ContextFactory
         throw new IllegalArgumentException(String.valueOf(featureIndex));
     }
 
+
+    /**
+     * Create class loader for generated classes.
+     * This method creates an instance of the default implementation
+     * of {@link GeneratedClassLoader}. Rhino uses this interface to load
+     * generated JVM classes when no {@link SecurityController}
+     * is installed.
+     * Application can override the method to provide custom class loading.
+     */
+    protected GeneratedClassLoader createClassLoader(ClassLoader parent)
+    {
+        return new DefiningClassLoader(parent);
+    }
+
     /**
      * Execute top call to script or function.
      * When the runtime is about to execute a script or function that will

js/rhino/src/org/mozilla/javascript/optimizer/Codegen.java

@@ -105,16 +105,19 @@ public class Codegen extends Interpreter
         return f;
     }
 
-    private static Class defineClass(Object bytecode,
-                                     Object staticSecurityDomain)
+    private Class defineClass(Object bytecode,
+                              Object staticSecurityDomain)
     {
         Object[] nameBytesPair = (Object[])bytecode;
         String className = (String)nameBytesPair[0];
         byte[] classBytes = (byte[])nameBytesPair[1];
 
+        // The generated classes in this case refer only to Rhino classes
+        // which must be accessible through this class loader
+        ClassLoader rhinoLoader = getClass().getClassLoader();
         GeneratedClassLoader loader;
-        loader = SecurityController.createLoader(null, staticSecurityDomain);
-
+        loader = SecurityController.createLoader(rhinoLoader,
+                                                 staticSecurityDomain);
         Exception e;
         try {
             Class cl = loader.defineClass(className, classBytes);