Convert the PDFDocumentProxy class, in src/display/api.js, to ES6 syntax

Moreover, indicate that a member are private and improve the comments to
be more consistent.

src/display/api.js

@@ -577,92 +577,100 @@ var PDFDataRangeTransport = (function pdfDataRangeTransportClosure() {
 /**
  * Proxy to a PDFDocument in the worker thread. Also, contains commonly used
  * properties that can be read synchronously.
- * @class
- * @alias PDFDocumentProxy
  */
-var PDFDocumentProxy = (function PDFDocumentProxyClosure() {
+class PDFDocumentProxy {
-  function PDFDocumentProxy(pdfInfo, transport, loadingTask) {
+  constructor(pdfInfo, transport, loadingTask) {
-    this._pdfInfo = pdfInfo;
-    this.transport = transport;
     this.loadingTask = loadingTask;
+
+    this._pdfInfo = pdfInfo;
+    this._transport = transport;
   }
-  PDFDocumentProxy.prototype = /** @lends PDFDocumentProxy.prototype */ {
+
   /**
    * @return {number} Total number of pages the PDF contains.
    */
   get numPages() {
     return this._pdfInfo.numPages;
-    },
+  }
+
   /**
-     * @return {string} A unique ID to identify a PDF. Not guaranteed to be
+   * @return {string} A (not guaranteed to be) unique ID to identify a PDF.
-     * unique.
    */
   get fingerprint() {
     return this._pdfInfo.fingerprint;
-    },
+  }
+
   /**
-     * @param {number} pageNumber The page number to get. The first page is 1.
+   * @param {number} pageNumber - The page number to get. The first page is 1.
    * @return {Promise} A promise that is resolved with a {@link PDFPageProxy}
    *   object.
    */
   getPage(pageNumber) {
-      return this.transport.getPage(pageNumber);
+    return this._transport.getPage(pageNumber);
-    },
+  }
+
   /**
-     * @param {{num: number, gen: number}} ref The page reference. Must have
+   * @param {{num: number, gen: number}} ref - The page reference. Must have
-     *   the 'num' and 'gen' properties.
+   *   the `num` and `gen` properties.
    * @return {Promise} A promise that is resolved with the page index that is
    *   associated with the reference.
    */
-    getPageIndex: function PDFDocumentProxy_getPageIndex(ref) {
+  getPageIndex(ref) {
-      return this.transport.getPageIndex(ref);
+    return this._transport.getPageIndex(ref);
-    },
+  }
+
   /**
    * @return {Promise} A promise that is resolved with a lookup table for
    *   mapping named destinations to reference numbers.
    *
-     * This can be slow for large documents: use getDestination instead
+   * This can be slow for large documents. Use `getDestination` instead.
    */
-    getDestinations: function PDFDocumentProxy_getDestinations() {
+  getDestinations() {
-      return this.transport.getDestinations();
+    return this._transport.getDestinations();
-    },
+  }
+
   /**
    * @param {string} id - The named destination to get.
    * @return {Promise} A promise that is resolved with all information
    *   of the given named destination.
    */
-    getDestination: function PDFDocumentProxy_getDestination(id) {
+  getDestination(id) {
-      return this.transport.getDestination(id);
+    return this._transport.getDestination(id);
-    },
+  }
+
   /**
-     * @return {Promise} A promise that is resolved with:
+   * @return {Promise} A promise that is resolved with an {Array} containing
-     *   an Array containing the pageLabels that correspond to the pageIndexes,
+   *   the page labels that correspond to the page indexes, or `null` when
-     *   or `null` when no pageLabels are present in the PDF file.
+   *   no page labels are present in the PDF file.
    */
-    getPageLabels: function PDFDocumentProxy_getPageLabels() {
+  getPageLabels() {
-      return this.transport.getPageLabels();
+    return this._transport.getPageLabels();
-    },
+  }
+
   /**
    * @return {Promise} A promise that is resolved with a {string} containing
-     *   the PageMode name.
+   *   the page mode name.
    */
   getPageMode() {
-      return this.transport.getPageMode();
+    return this._transport.getPageMode();
-    },
+  }
+
   /**
    * @return {Promise} A promise that is resolved with a lookup table for
    *   mapping named attachments to their content.
    */
-    getAttachments: function PDFDocumentProxy_getAttachments() {
+  getAttachments() {
-      return this.transport.getAttachments();
+    return this._transport.getAttachments();
-    },
+  }
+
   /**
    * @return {Promise} A promise that is resolved with an {Array} of all the
    *   JavaScript strings in the name tree, or `null` if no JavaScript exists.
    */
   getJavaScript() {
-      return this.transport.getJavaScript();
+    return this._transport.getJavaScript();
-    },
+  }
+
   /**
    * @return {Promise} A promise that is resolved with an {Array} that is a
    * tree outline (if it has one) of the PDF. The tree is in the format of:
@@ -677,54 +685,61 @@ var PDFDocumentProxy = (function PDFDocumentProxyClosure() {
    *     items: array of more items like this
    *   },
    *   ...
-     * ].
+   * ]
    */
-    getOutline: function PDFDocumentProxy_getOutline() {
+  getOutline() {
-      return this.transport.getOutline();
+    return this._transport.getOutline();
-    },
+  }
+
   /**
    * @return {Promise} A promise that is resolved with an {Object} that has
-     * info and metadata properties.  Info is an {Object} filled with anything
+   *   `info` and `metadata` properties. `info` is an {Object} filled with
-     * available in the information dictionary and similarly metadata is a
+   *   anything available in the information dictionary and similarly
-     * {Metadata} object with information from the metadata section of the PDF.
+   *   `metadata` is a {Metadata} object with information from the metadata
+   *   section of the PDF.
    */
-    getMetadata: function PDFDocumentProxy_getMetadata() {
+  getMetadata() {
-      return this.transport.getMetadata();
+    return this._transport.getMetadata();
-    },
+  }
+
   /**
-     * @return {Promise} A promise that is resolved with a TypedArray that has
+   * @return {Promise} A promise that is resolved with a {TypedArray} that has
    * the raw data from the PDF.
    */
-    getData: function PDFDocumentProxy_getData() {
+  getData() {
-      return this.transport.getData();
+    return this._transport.getData();
-    },
+  }
+
   /**
    * @return {Promise} A promise that is resolved when the document's data
-     * is loaded. It is resolved with an {Object} that contains the length
+   *   is loaded. It is resolved with an {Object} that contains the `length`
    *   property that indicates size of the PDF data in bytes.
    */
-    getDownloadInfo: function PDFDocumentProxy_getDownloadInfo() {
+  getDownloadInfo() {
-      return this.transport.downloadInfoCapability.promise;
+    return this._transport.downloadInfoCapability.promise;
-    },
+  }
+
   /**
-     * @return {Promise} A promise this is resolved with current stats about
+   * @return {Promise} A promise this is resolved with current statistics about
    *   document structures (see {@link PDFDocumentStats}).
    */
-    getStats: function PDFDocumentProxy_getStats() {
+  getStats() {
-      return this.transport.getStats();
+    return this._transport.getStats();
-    },
+  }
+
   /**
-     * Cleans up resources allocated by the document, e.g. created @font-face.
+   * Cleans up resources allocated by the document, e.g. created `@font-face`.
    */
-    cleanup: function PDFDocumentProxy_cleanup() {
+  cleanup() {
-      this.transport.startCleanup();
+    this._transport.startCleanup();
-    },
+  }
+
   /**
-     * Destroys current document instance and terminates worker.
+   * Destroys the current document instance and terminates the worker.
    */
-    destroy: function PDFDocumentProxy_destroy() {
+  destroy() {
     return this.loadingTask.destroy();
-    },
+  }
 
   /**
    * @return {Object} A subset of the current {DocumentInitParameters},
@@ -732,11 +747,9 @@ var PDFDocumentProxy = (function PDFDocumentProxyClosure() {
    *   may be affected by the `apiCompatibilityParams`.
    */
   get loadingParams() {
-      return this.transport.loadingParams;
+    return this._transport.loadingParams;
-    },
+  }
-  };
+}
-  return PDFDocumentProxy;
-})();
 
 /**
  * Page getTextContent parameters.