ChromeVox: Fix closure errors by removing calls to goog.isDef().

Bug: N/A
Change-Id: Ibc913eaefe212b621b7ffdd83e05bdd75f62920b
AX-Relnotes: N/A
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2480733Reviewed-by: David Tseng <dtseng@chromium.org>
Commit-Queue: Akihiro Ota <akihiroota@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818544}

chrome/browser/resources/chromeos/accessibility/chromevox/background/cursors.js

@@ -458,7 +458,7 @@ cursors.Cursor = class {
         throw Error('Unrecognized unit: ' + unit);
     }
     newNode = newNode || originalNode;
-    newIndex = goog.isDef(newIndex) ? newIndex : this.index_;
+    newIndex = (newIndex !== undefined) ? newIndex : this.index_;
     return new cursors.Cursor(newNode, newIndex);
   }
 

chrome/browser/resources/chromeos/accessibility/chromevox/braille/braille_input_handler.js

@@ -406,7 +406,7 @@ BrailleInputHandler = class {
         // so that these keys work even if the Braille IME is not active.
         const keyName = /** @type {string} */ (event.standardKeyCode);
         const numericCode = BrailleKeyEvent.keyCodeToLegacyCode(keyName);
-        if (!goog.isDef(numericCode)) {
+        if (!numericCode) {
           throw Error('Unknown key code in event: ' + JSON.stringify(event));
         }
         EventGenerator.sendKeyPress(numericCode, {

chrome/browser/resources/chromeos/accessibility/chromevox/braille/liblouis.js

@@ -32,8 +32,7 @@ LibLouis = class {
      * Path to translation tables.
      * @private {?string}
      */
-    this.tablesDir_ = goog.isDef(opt_tablesDir) ? opt_tablesDir : null;
-
+    this.tablesDir_ = (opt_tablesDir !== undefined) ? opt_tablesDir : null;
 
     /**
      * Whether liblouis is loaded.

chrome/browser/resources/chromeos/accessibility/chromevox/braille/nav_braille.js

@@ -39,14 +39,15 @@ NavBraille = class {
      * Selection start index.
      * @type {number}
      */
-    this.startIndex = goog.isDef(kwargs.startIndex) ? kwargs.startIndex : -1;
+    this.startIndex =
+        (kwargs.startIndex !== undefined) ? kwargs.startIndex : -1;
 
     /**
      * Selection end index.
      * @type {number}
      */
     this.endIndex =
-        goog.isDef(kwargs.endIndex) ? kwargs.endIndex : this.startIndex;
+        (kwargs.endIndex !== undefined) ? kwargs.endIndex : this.startIndex;
   }
 
   /**