Rename BaseViewer._setDocumentViewerElement to BaseViewer._viewerElement

It was pointed out the the old name felt confusing, so let's just rename the getter since it's an internal property anyway.

web/base_viewer.js

@@ -391,9 +391,9 @@ class BaseViewer {
   /**
    * @private
    */
-  get _setDocumentViewerElement() {
+  get _viewerElement() {
     // In most viewers, e.g. `PDFViewer`, this should return `this.viewer`.
-    throw new Error("Not implemented: _setDocumentViewerElement");
+    throw new Error("Not implemented: _viewerElement");
   }
 
   /**
@@ -479,7 +479,7 @@ class BaseViewer {
 
         for (let pageNum = 1; pageNum <= pagesCount; ++pageNum) {
           const pageView = new PDFPageView({
-            container: this._setDocumentViewerElement,
+            container: this._viewerElement,
             eventBus: this.eventBus,
             id: pageNum,
             scale,

web/pdf_single_page_viewer.js

@@ -27,12 +27,12 @@ class PDFSinglePageViewer extends BaseViewer {
     });
   }
 
-  get _setDocumentViewerElement() {
+  get _viewerElement() {
     // Since we only want to display *one* page at a time when using the
     // `PDFSinglePageViewer`, we cannot append them to the `viewer` DOM element.
     // Instead, they are placed in a `DocumentFragment`, and only the current
     // page is displayed in the viewer (refer to `this._ensurePageViewVisible`).
-    return shadow(this, "_setDocumentViewerElement", this._shadowViewer);
+    return shadow(this, "_viewerElement", this._shadowViewer);
   }
 
   _resetView() {

web/pdf_viewer.js

@@ -17,8 +17,8 @@ import { BaseViewer } from "./base_viewer.js";
 import { shadow } from "pdfjs-lib";
 
 class PDFViewer extends BaseViewer {
-  get _setDocumentViewerElement() {
-    return shadow(this, "_setDocumentViewerElement", this.viewer);
+  get _viewerElement() {
+    return shadow(this, "_viewerElement", this.viewer);
   }
 
   _scrollIntoView({ pageDiv, pageSpot = null, pageNumber = null }) {