Remove the unused IPDFStreamRangeReader.prototype.isStreamingSupported getter

This getter was only invoked from `src/display/network.js` and `src/core/chunked_stream.js`, however in both cases it's hardcoded to `false` and thus isn't actually needed.
This originated in PR 6879, close to a decade ago, for a potential TODO which was never implemented and it ought to be OK to just simplify this now.

Author: Snuffleupagus

src/core/chunked_stream.js

@@ -283,19 +283,15 @@ class ChunkedStreamManager {
 
   sendRequest(begin, end) {
     const rangeReader = this.pdfNetworkStream.getRangeReader(begin, end);
-    if (!rangeReader.isStreamingSupported) {
-      rangeReader.onProgress = this.onProgress.bind(this);
-    }
+    rangeReader.onProgress = this.onProgress.bind(this);
 
-    let chunks = [],
-      loaded = 0;
+    let chunks = [];
     return new Promise((resolve, reject) => {
       const readChunk = ({ value, done }) => {
         try {
           if (done) {
-            const chunkData = arrayBuffersToBytes(chunks);
+            resolve(arrayBuffersToBytes(chunks));
             chunks = null;
-            resolve(chunkData);
             return;
           }
           if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
@@ -304,12 +300,6 @@ class ChunkedStreamManager {
               "readChunk (sendRequest) - expected an ArrayBuffer."
             );
           }
-          loaded += value.byteLength;
-
-          if (rangeReader.isStreamingSupported) {
-            this.onProgress({ loaded });
-          }
-
           chunks.push(value);
           rangeReader.read().then(readChunk, reject);
         } catch (e) {

src/core/worker_stream.js

@@ -114,10 +114,6 @@ class PDFWorkerStreamRangeReader {
     this._reader = readableStream.getReader();
   }
 
-  get isStreamingSupported() {
-    return false;
-  }
-
   async read() {
     const { value, done } = await this._reader.read();
     if (done) {

src/display/fetch_stream.js

@@ -209,7 +209,6 @@ class PDFFetchStreamRangeReader {
     const source = stream.source;
     this._withCredentials = source.withCredentials || false;
     this._readCapability = Promise.withResolvers();
-    this._isStreamingSupported = !source.disableStream;
 
     this._abortController = new AbortController();
     // Always create a copy of the headers.
@@ -240,10 +239,6 @@ class PDFFetchStreamRangeReader {
     this.onProgress = null;
   }
 
-  get isStreamingSupported() {
-    return this._isStreamingSupported;
-  }
-
   async read() {
     await this._readCapability.promise;
     const { value, done } = await this._reader.read();

src/display/network.js

@@ -413,13 +413,7 @@ class PDFNetworkStreamRangeRequestReader {
   }
 
   _onProgress(evt) {
-    if (!this.isStreamingSupported) {
-      this.onProgress?.({ loaded: evt.loaded });
-    }
-  }
-
-  get isStreamingSupported() {
-    return false;
+    this.onProgress?.({ loaded: evt.loaded });
   }
 
   async read() {

src/display/node_stream.js

@@ -208,8 +208,6 @@ class PDFNodeStreamFsRangeReader {
   constructor(stream, begin, end) {
     this.onProgress = null;
     this._loaded = 0;
-    const source = stream.source;
-    this._isStreamingSupported = !source.disableStream;
 
     const url = stream.url;
     const fs = process.getBuiltinModule("fs");
@@ -228,10 +226,6 @@ class PDFNodeStreamFsRangeReader {
     }
   }
 
-  get isStreamingSupported() {
-    return this._isStreamingSupported;
-  }
-
   async read() {
     await this._readCapability.promise;
     const { value, done } = await this._reader.read();

src/display/transport_stream.js

@@ -287,10 +287,6 @@ class PDFDataTransportStreamRangeReader {
     this._stream._removeRangeReader(this);
   }
 
-  get isStreamingSupported() {
-    return false;
-  }
-
   async read() {
     if (this._queuedChunk) {
       const chunk = this._queuedChunk;

src/interfaces.js

@@ -145,14 +145,6 @@ class IPDFStreamRangeReader {
     this.onProgress = null;
   }
 
-  /**
-   * Gets ability of the stream to progressively load binary data.
-   * @type {boolean}
-   */
-  get isStreamingSupported() {
-    return false;
-  }
-
   /**
    * Requests a chunk of the binary data. The method returns the promise, which
    * is resolved into object with properties "value" and "done". If the done