Stop using the source-object when sending "GetDocRequest"

Looking at the code on the worker-thread, there doesn't appear to be any particular reason for placing *some* of the properties in a `source`-object when sending them with "GetDocRequest".
As is often the case the explanation for this structure is rather "for historical reasons", since originally we simply sent the `source`-object as-is. Doing that was obviously a bad idea, for a couple of reasons:
 - It makes it less clear what is/isn't actually needed on the worker-thread.
 - Sending unused properties will unnecessarily increase memory usage.
 - The `source`-object may contain unclonable data, which would break the library.

src/core/worker.js

@@ -97,7 +97,7 @@ class WorkerMessageHandler {
     const WorkerTasks = [];
     const verbosity = getVerbosityLevel();
 
-    const apiVersion = docParams.apiVersion;
+    const { docId, apiVersion } = docParams;
     const workerVersion =
       typeof PDFJSDev !== "undefined" && !PDFJSDev.test("TESTING")
         ? PDFJSDev.eval("BUNDLE_VERSION")
@@ -142,10 +142,7 @@ class WorkerMessageHandler {
         throw new Error(partialMsg + "please update to a supported browser.");
       }
     }
-
-    const docId = docParams.docId;
-    const docBaseUrl = docParams.docBaseUrl;
-    const workerHandlerName = docParams.docId + "_worker";
+    const workerHandlerName = docId + "_worker";
     let handler = new MessageHandler(workerHandlerName, docId, port);
 
     function ensureNotTerminated() {
@@ -204,17 +201,25 @@ class WorkerMessageHandler {
       return { numPages, fingerprints, htmlForXfa };
     }
 
-    function getPdfManager(data, evaluatorOptions, enableXfa) {
+    function getPdfManager({
+      data,
+      password,
+      disableAutoFetch,
+      rangeChunkSize,
+      length,
+      docBaseUrl,
+      enableXfa,
+      evaluatorOptions,
+    }) {
       const pdfManagerCapability = createPromiseCapability();
       let newPdfManager;
 
-      const source = data.source;
-      if (source.data) {
+      if (data) {
         try {
           newPdfManager = new LocalPdfManager(
             docId,
-            source.data,
-            source.password,
+            data,
+            password,
             handler,
             evaluatorOptions,
             enableXfa,
@@ -242,19 +247,19 @@ class WorkerMessageHandler {
           if (!fullRequest.isRangeSupported) {
             return;
           }
-
           // We don't need auto-fetch when streaming is enabled.
-          const disableAutoFetch =
-            source.disableAutoFetch || fullRequest.isStreamingSupported;
+          disableAutoFetch =
+            disableAutoFetch || fullRequest.isStreamingSupported;
+
           newPdfManager = new NetworkPdfManager(
             docId,
             pdfStream,
             {
               msgHandler: handler,
-              password: source.password,
+              password,
               length: fullRequest.contentLength,
               disableAutoFetch,
-              rangeChunkSize: source.rangeChunkSize,
+              rangeChunkSize,
             },
             evaluatorOptions,
             enableXfa,
@@ -279,7 +284,7 @@ class WorkerMessageHandler {
       let loaded = 0;
       const flushChunks = function () {
         const pdfFile = arraysToBytes(cachedChunks);
-        if (source.length && pdfFile.length !== source.length) {
+        if (length && pdfFile.length !== length) {
           warn("reported HTTP length is different from actual");
         }
         // the data is array, instantiating directly from it
@@ -287,7 +292,7 @@ class WorkerMessageHandler {
           newPdfManager = new LocalPdfManager(
             docId,
             pdfFile,
-            source.password,
+            password,
             handler,
             evaluatorOptions,
             enableXfa,
@@ -405,7 +410,7 @@ class WorkerMessageHandler {
 
       ensureNotTerminated();
 
-      getPdfManager(data, data.evaluatorOptions, data.enableXfa)
+      getPdfManager(data)
         .then(function (newPdfManager) {
           if (terminated) {
             // We were in a process of setting up the manager, but it got

src/display/api.js

@@ -503,20 +503,18 @@ async function _fetchDocument(worker, source, pdfDataRangeTransport, docId) {
   }
   const workerId = await worker.messageHandler.sendWithPromise(
     "GetDocRequest",
+    // Only send the required properties, and *not* the entire `source` object.
     {
       docId,
       apiVersion:
         typeof PDFJSDev !== "undefined" && !PDFJSDev.test("TESTING")
           ? PDFJSDev.eval("BUNDLE_VERSION")
           : null,
-      // Only send the required properties, and *not* the entire object.
-      source: {
-        data: source.data,
-        password: source.password,
-        disableAutoFetch: source.disableAutoFetch,
-        rangeChunkSize: source.rangeChunkSize,
-        length: source.length,
-      },
+      data: source.data,
+      password: source.password,
+      disableAutoFetch: source.disableAutoFetch,
+      rangeChunkSize: source.rangeChunkSize,
+      length: source.length,
       docBaseUrl: source.docBaseUrl,
       enableXfa: source.enableXfa,
       evaluatorOptions: {