Use ESLint to ensure that exports are sorted alphabetically

There's built-in ESLint rule, see `sort-imports`, to ensure that all `import`-statements are sorted alphabetically, since that often helps with readability.
Unfortunately there's no corresponding rule to sort `export`-statements alphabetically, however there's an ESLint plugin which does this; please see https://www.npmjs.com/package/eslint-plugin-sort-exports

The only downside here is that it's not automatically fixable, but the re-ordering is a one-time "cost" and the plugin will help maintain a *consistent* ordering of `export`-statements in the future.
*Note:* To reduce the possibility of introducing any errors here, the re-ordering was done by simply selecting the relevant lines and then using the built-in sort-functionality of my editor.

web/ui_utils.js

@@ -1031,46 +1031,46 @@ function getActiveOrFocusedElement() {
 }
 
 export {
+  animationStarted,
+  approximateFraction,
   AutoPrintRegExp,
+  backtrackBeforeAllVisibleElements, // only exported for testing
+  binarySearchFirstItem,
   CSS_UNITS,
-  DEFAULT_SCALE_VALUE,
   DEFAULT_SCALE,
-  MIN_SCALE,
-  MAX_SCALE,
-  UNKNOWN_SCALE,
-  MAX_AUTO_SCALE,
-  SCROLLBAR_PADDING,
-  VERTICAL_PADDING,
+  DEFAULT_SCALE_VALUE,
+  EventBus,
+  getActiveOrFocusedElement,
+  getOutputScale,
+  getPageSizeInches,
+  getPDFFileNameFromURL,
+  getVisibleElements,
+  isPortraitOrientation,
   isValidRotation,
   isValidScrollMode,
   isValidSpreadMode,
-  isPortraitOrientation,
-  PresentationModeState,
-  SidebarView,
-  RendererType,
-  TextLayerMode,
-  ScrollMode,
-  SpreadMode,
-  NullL10n,
-  EventBus,
-  ProgressBar,
-  getPDFFileNameFromURL,
-  noContextMenuHandler,
-  parseQueryString,
-  backtrackBeforeAllVisibleElements, // only exported for testing
-  getVisibleElements,
-  roundToDivide,
-  getPageSizeInches,
-  approximateFraction,
-  getOutputScale,
-  scrollIntoView,
-  watchScroll,
-  binarySearchFirstItem,
-  normalizeWheelEventDirection,
-  normalizeWheelEventDelta,
-  animationStarted,
-  WaitOnType,
-  waitOnEventOrTimeout,
+  MAX_AUTO_SCALE,
+  MAX_SCALE,
+  MIN_SCALE,
   moveToEndOfArray,
-  getActiveOrFocusedElement,
+  noContextMenuHandler,
+  normalizeWheelEventDelta,
+  normalizeWheelEventDirection,
+  NullL10n,
+  parseQueryString,
+  PresentationModeState,
+  ProgressBar,
+  RendererType,
+  roundToDivide,
+  SCROLLBAR_PADDING,
+  scrollIntoView,
+  ScrollMode,
+  SidebarView,
+  SpreadMode,
+  TextLayerMode,
+  UNKNOWN_SCALE,
+  VERTICAL_PADDING,
+  waitOnEventOrTimeout,
+  WaitOnType,
+  watchScroll,
 };