[api-minor] Change the getViewport method, on PDFPageProxy, to take a parameter object rather than a bunch of (randomly) ordered parameters

If, as PR 10368 suggests, more parameters should be added to `getViewport` I think that it would be a mistake to not change the signature *first* to avoid needlessly unwieldy call-sites.

To not break any existing code and third-party use-cases, this is obviously implemented with a deprecation warning *and* with a working fallback[1] for the old method signature.

---
[1] This is limited to `GENERIC` builds, which should be sufficient.

web/base_viewer.js

@@ -419,7 +419,7 @@ class BaseViewer {
     // viewport for all pages
     firstPagePromise.then((pdfPage) => {
       let scale = this.currentScale;
-      let viewport = pdfPage.getViewport(scale * CSS_UNITS);
+      let viewport = pdfPage.getViewport({ scale: scale * CSS_UNITS, });
       for (let pageNum = 1; pageNum <= pagesCount; ++pageNum) {
         let textLayerFactory = null;
         if (this.textLayerMode !== TextLayerMode.DISABLE) {
@@ -1031,7 +1031,7 @@ class BaseViewer {
    */
   getPagesOverview() {
     let pagesOverview = this._pages.map(function(pageView) {
-      let viewport = pageView.pdfPage.getViewport(1);
+      let viewport = pageView.pdfPage.getViewport({ scale: 1, });
       return {
         width: viewport.width,
         height: viewport.height,

web/firefox_print_service.js

@@ -48,7 +48,7 @@ function composePage(pdfDocument, pageNumber, size, printContainer) {
       let renderContext = {
         canvasContext: ctx,
         transform: [PRINT_UNITS, 0, 0, PRINT_UNITS, 0, 0],
-        viewport: pdfPage.getViewport(1, size.rotation),
+        viewport: pdfPage.getViewport({ scale: 1, rotation: size.rotation, }),
         intent: 'print',
       };
       return pdfPage.render(renderContext).promise;

web/pdf_page_view.js

@@ -118,8 +118,8 @@ class PDFPageView {
     this.pdfPageRotate = pdfPage.rotate;
 
     let totalRotation = (this.rotation + this.pdfPageRotate) % 360;
-    this.viewport = pdfPage.getViewport(this.scale * CSS_UNITS,
-                                        totalRotation);
+    this.viewport = pdfPage.getViewport({ scale: this.scale * CSS_UNITS,
+                                          rotation: totalRotation, });
     this.stats = pdfPage.stats;
     this.reset();
   }

web/pdf_print_service.js

@@ -45,7 +45,7 @@ function renderPage(activeServiceOnEntry, pdfDocument, pageNumber, size) {
     let renderContext = {
       canvasContext: ctx,
       transform: [PRINT_UNITS, 0, 0, PRINT_UNITS, 0, 0],
-      viewport: pdfPage.getViewport(1, size.rotation),
+      viewport: pdfPage.getViewport({ scale: 1, rotation: size.rotation, }),
       intent: 'print',
     };
     return pdfPage.render(renderContext).promise;

web/pdf_thumbnail_view.js

@@ -146,7 +146,7 @@ class PDFThumbnailView {
     this.pdfPage = pdfPage;
     this.pdfPageRotate = pdfPage.rotate;
     let totalRotation = (this.rotation + this.pdfPageRotate) % 360;
-    this.viewport = pdfPage.getViewport(1, totalRotation);
+    this.viewport = pdfPage.getViewport({ scale: 1, rotation: totalRotation, });
     this.reset();
   }
 

web/pdf_thumbnail_viewer.js

@@ -166,7 +166,7 @@ class PDFThumbnailViewer {
 
     pdfDocument.getPage(1).then((firstPage) => {
       let pagesCount = pdfDocument.numPages;
-      let viewport = firstPage.getViewport(1.0);
+      let viewport = firstPage.getViewport({ scale: 1, });
       for (let pageNum = 1; pageNum <= pagesCount; ++pageNum) {
         let thumbnail = new PDFThumbnailView({
           container: this.container,