Remove unnecessary closure in src/display/text_layer.js, and use standard classes

With modern JavaScript modules, where you explicitly list the properties that should be exported, it's no longer necessary to wrap all of the code in a closure.[1]

This patch also tries to clean-up/improve a couple of the existing JSDoc-comments.

---
[1] This reduces the size, even of the *built* `pdf.js` file, since there's now a lot less unnecessary whitespace.

src/display/text_layer.js

@@ -42,17 +42,6 @@ import {
  *   selection enhancement.
  */
 
-/**
- * @typedef {Object} TextLayerRenderTask
- * @property {Promise<void>} promise
- * @property {() => void} cancel
- * @property {(expandDivs: boolean) => void} expandTextDivs
- */
-
-/**
- * @type {(renderParameters: TextLayerRenderParameters) => TextLayerRenderTask}
- */
-const renderTextLayer = (function renderTextLayerClosure() {
 const MAX_TEXT_DIVS_TO_RENDER = 100000;
 const DEFAULT_FONT_SIZE = 30;
 const DEFAULT_FONT_ASCENT = 0.8;
@@ -138,7 +127,6 @@ const renderTextLayer = (function renderTextLayerClosure() {
     scale: 1,
   };
 
-    textDiv.textContent = geom.str;
   task._textDivs.push(textDiv);
 
   const tx = Util.transform(task._viewport.transform, geom.transform);
@@ -168,6 +156,7 @@ const renderTextLayer = (function renderTextLayerClosure() {
   // Keeps screen readers from pausing on every new text span.
   textDiv.setAttribute("role", "presentation");
 
+  textDiv.textContent = geom.str;
   // geom.dir may be 'ttb' for vertical texts.
   textDiv.dir = geom.dir;
 
@@ -561,17 +550,8 @@ const renderTextLayer = (function renderTextLayerClosure() {
   }
 }
 
-  /**
-   * Text layer rendering task.
-   *
-   * @param {TextContent} textContent
-   * @param {HTMLElement} container
-   * @param {PageViewport} viewport
-   * @param {Array} textDivs
-   * @param {boolean} enhanceTextSelection
-   * @private
-   */
-  function TextLayerRenderTask({
+class TextLayerRenderTask {
+  constructor({
     textContent,
     textContentStream,
     container,
@@ -616,12 +596,19 @@ const renderTextLayer = (function renderTextLayerClosure() {
         /* Avoid "Uncaught promise" messages in the console. */
       });
   }
-  TextLayerRenderTask.prototype = {
+
+  /**
+   * Promise for textLayer rendering task completion.
+   * @type {Promise<void>}
+   */
   get promise() {
     return this._capability.promise;
-    },
+  }
 
-    cancel: function TextLayer_cancel() {
+  /**
+   * Cancel rendering of the textLayer.
+   */
+  cancel() {
     this._canceled = true;
     if (this._reader) {
       this._reader.cancel(new AbortException("TextLayer task cancelled."));
@@ -632,8 +619,11 @@ const renderTextLayer = (function renderTextLayerClosure() {
       this._renderTimer = null;
     }
     this._capability.reject(new Error("TextLayer task cancelled."));
-    },
+  }
 
+  /**
+   * @private
+   */
   _processItems(items, styleCache) {
     for (let i = 0, len = items.length; i < len; i++) {
       if (items[i].str === undefined) {
@@ -656,8 +646,11 @@ const renderTextLayer = (function renderTextLayerClosure() {
       this._textContentItemsStr.push(items[i].str);
       appendText(this, items[i], styleCache, this._layoutTextCtx);
     }
-    },
+  }
 
+  /**
+   * @private
+   */
   _layoutText(textDiv) {
     const textDivProperties = this._textDivProperties.get(textDiv);
 
@@ -700,9 +693,12 @@ const renderTextLayer = (function renderTextLayerClosure() {
       br.setAttribute("role", "presentation");
       this._container.appendChild(br);
     }
-    },
+  }
 
-    _render: function TextLayer_render(timeout) {
+  /**
+   * @private
+   */
+  _render(timeout = 0) {
     const capability = createPromiseCapability();
     let styleCache = Object.create(null);
 
@@ -759,9 +755,12 @@ const renderTextLayer = (function renderTextLayerClosure() {
         }, timeout);
       }
     }, this._capability.reject);
-    },
+  }
 
-    expandTextDivs: function TextLayer_expandTextDivs(expandDivs) {
+  /**
+   * @param {boolean} [expandDivs]
+   */
+  expandTextDivs(expandDivs = false) {
     if (!this._enhanceTextSelection || !this._renderingDone) {
       return;
     }
@@ -820,10 +819,13 @@ const renderTextLayer = (function renderTextLayerClosure() {
         div.style.transform = divProps.originalTransform;
       }
     }
-    },
-  };
+  }
+}
 
-  // eslint-disable-next-line no-shadow
+/**
+ * @param {TextLayerRenderParameters} renderParameters
+ * @returns {TextLayerRenderTask}
+ */
 function renderTextLayer(renderParameters) {
   const task = new TextLayerRenderTask({
     textContent: renderParameters.textContent,
@@ -838,7 +840,4 @@ const renderTextLayer = (function renderTextLayerClosure() {
   return task;
 }
 
-  return renderTextLayer;
-})();
-
 export { renderTextLayer };