Fix inconsistent spacing and trailing commas in objects in web/ files, so we can enable the comma-dangle and object-curly-spacing ESLint rules later on

http://eslint.org/docs/rules/comma-dangle
http://eslint.org/docs/rules/object-curly-spacing

Given that we currently have quite inconsistent object formatting, fixing this in in *one* big patch probably wouldn't be feasible (since I cannot imagine anyone wanting to review that); hence I've opted to try and do this piecewise instead.

*Please note:* This patch was created automatically, using the ESLint `--fix` command line option. In a couple of places this caused lines to become too long, and I've fixed those manually; please refer to the interdiff below for the only hand-edits in this patch.

```diff
diff --git a/web/pdf_thumbnail_view.js b/web/pdf_thumbnail_view.js
index 002dbf29..1de4e530 100644
--- a/web/pdf_thumbnail_view.js
+++ b/web/pdf_thumbnail_view.js
@@ -420,8 +420,8 @@ var PDFThumbnailView = (function PDFThumbnailViewClosure() {
     setPageLabel: function PDFThumbnailView_setPageLabel(label) {
       this.pageLabel = (typeof label === 'string' ? label : null);

-      this.l10n.get('thumb_page_title', { page: this.pageId, }, 'Page {{page}}').
-          then((msg) => {
+      this.l10n.get('thumb_page_title', { page: this.pageId, },
+                    'Page {{page}}').then((msg) => {
         this.anchor.title = msg;
       });

diff --git a/web/secondary_toolbar.js b/web/secondary_toolbar.js
index 160e0410..6495fc5e 100644
--- a/web/secondary_toolbar.js
+++ b/web/secondary_toolbar.js
@@ -65,7 +65,8 @@ class SecondaryToolbar {
       { element: options.printButton, eventName: 'print', close: true, },
       { element: options.downloadButton, eventName: 'download', close: true, },
       { element: options.viewBookmarkButton, eventName: null, close: true, },
-      { element: options.firstPageButton, eventName: 'firstpage', close: true, },
+      { element: options.firstPageButton, eventName: 'firstpage',
+        close: true, },
       { element: options.lastPageButton, eventName: 'lastpage', close: true, },
       { element: options.pageRotateCwButton, eventName: 'rotatecw',
         close: false, },
@@ -76,7 +77,7 @@ class SecondaryToolbar {
       { element: options.cursorHandToolButton, eventName: 'switchcursortool',
         eventDetails: { tool: CursorTool.HAND, }, close: true, },
       { element: options.documentPropertiesButton,
-        eventName: 'documentproperties', close: true, }
+        eventName: 'documentproperties', close: true, },
     ];
     this.items = {
       firstPage: options.firstPageButton,
```

web/annotation_layer_builder.js

@@ -49,7 +49,7 @@ class AnnotationLayerBuilder {
   render(viewport, intent = 'display') {
     this.pdfPage.getAnnotations({ intent, }).then((annotations) => {
       var parameters = {
-        viewport: viewport.clone({ dontFlip: true }),
+        viewport: viewport.clone({ dontFlip: true, }),
         div: this.div,
         annotations,
         page: this.pdfPage,