Fix the remaining cases of inconsistent spacing and trailing commas in objects, and enable the comma-dangle and object-curly-spacing ESLint rules

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

*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/gulpfile.js b/gulpfile.js
index d18b9c58..7d47fd8d 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -1247,7 +1247,8 @@ gulp.task('gh-pages-git', ['gh-pages-prepare', 'wintersmith'], function () {
   var reason = process.env['PDFJS_UPDATE_REASON'];

   safeSpawnSync('git', ['init'], { cwd: GH_PAGES_DIR, });
-  safeSpawnSync('git', ['remote', 'add', 'origin', REPO], { cwd: GH_PAGES_DIR, });
+  safeSpawnSync('git', ['remote', 'add', 'origin', REPO],
+                { cwd: GH_PAGES_DIR, });
   safeSpawnSync('git', ['add', '-A'], { cwd: GH_PAGES_DIR, });
   safeSpawnSync('git', [
     'commit', '-am', 'gh-pages site created via gulpfile.js script',
```

external/builder/builder.js

@@ -53,7 +53,7 @@ function preprocess(inFilename, outFilename, defines) {
       throw new Error('No JavaScript expression given at ' + loc());
     }
     try {
-      return vm.runInNewContext(code, defines, {displayErrors: false});
+      return vm.runInNewContext(code, defines, { displayErrors: false, });
     } catch (e) {
       throw new Error('Could not evaluate "' + code + '" at ' + loc() + '\n' +
                       e.name + ': ' + e.message);