Fix issue with IE WebWorker
Fix issue with IE WebWorker

jimmywarting/Dexie.js,dfahlander/Dexie.js,chrahunt/Dexie.js,jimmywarting/Dexie.js,dfahlander/Dexie.js,chrahunt/Dexie.js,jimmywarting/Dexie.js,dfahlander/Dexie.js,jimmywarting/Dexie.js,chrahunt/Dexie.js,dfahlander/Dexie.js,chrahunt/Dexie.js