Add offsetof<T> builtin; Put a function's trampoline into the function table if a it has optional parameters; TypedArray scaffolding

src/program.ts

@@ -3012,7 +3012,7 @@ export class ClassPrototype extends Element {
         }
       }
     }
-    instance.currentMemoryOffset = memoryOffset; // sizeof<this>() is its byte size in memory
+    instance.currentMemoryOffset = memoryOffset; // offsetof<this>() is the class' byte size in memory
     return instance;
   }