[wasm] Fix threaded worker blob syntax error (#6214)

JS's Blob replaces "\n" with a newline character. In the threaded worker bundle, there's a "\n" in `if(ENVIRONMENT_IS_NODE){fs.writeSync(2,text+"\n")`. When it is replaced with a newline, it splits a string across multiple lines, which is not valid JavaScript.

This change prevents Blob from doing that replacement by escaping the "\n" character as "\\n".

fixes #6203

Author: mattsoulanille

tfjs-backend-wasm/src/backend_wasm.ts

@@ -292,7 +292,10 @@ export async function init(): Promise<{wasm: BackendWasmModule}> {
      */
     factoryConfig.locateFile = (path, prefix) => {
       if (path.endsWith('.worker.js')) {
-        const response = wasmWorkerContents;
+        // Escape '\n' because Blob will turn it into a newline.
+        // There should be a setting for this, but 'endings: "native"' does
+        // not seem to work.
+        const response = (wasmWorkerContents as string).replace(/\n/g, '\\n');
         const blob = new Blob([response], {type: 'application/javascript'});
         return URL.createObjectURL(blob);
       }