Cherry-pick commit f821bf5 in wasm_worker.js

Author: kleisauke

src/wasm_worker.js

@@ -26,7 +26,7 @@ if (ENVIRONMENT_IS_NODE) {
 		},
 		Worker: nodeWorkerThreads.Worker,
 		importScripts: function(f) {
-			(0, eval)(fs.readFileSync(f, 'utf8'));
+			(0, eval)(fs.readFileSync(f, 'utf8') + '//# sourceURL=' + f);
 		},
 		postMessage: function(msg) {
 			parentPort.postMessage(msg);