Fixes error to extract constructor name using build --prod

[leandrogehlen]

Short description of what this resolves:

Fixes error to extract constructor name using build --prod

Fixes:
When we needs extract constructor name from class, (like migrations), usinb build --prod the
uglify process can't do it.

Example

class  m201707121646_create_post {
  up(): Array<string> {
       return [
         `ALTER TABLE "post" ALTER COLUMN "title" RENAME TO "name"`,
         `ALTER TABLE "post" ADD COLUMN "category_id" INTEGER`
       ];
   }
}

const MIGRATIONS: Array<any> = [
 m201707121646_criar_pessoa
];

MIGRATIONS.forEach((migration) => {
     const instance = new migration();
     console.log((<any>instance).constructor.name);    
}