Use default value in undefined check if provided

Change-Id: Icff2a8b17e4f8be50c1af462def4140140533feb

polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js

@@ -1048,7 +1048,7 @@
     _computeReplyButtonLabel(changeRecord, canStartReview) {
       // Polymer 2: check for undefined
       if ([changeRecord, canStartReview].some(arg => arg === undefined)) {
-        return undefined;
+        return 'Reply';
       }
 
       if (canStartReview) {

polygerrit-ui/app/elements/change/gr-download-dialog/gr-download-dialog.js

@@ -159,7 +159,7 @@
     _computeSchemes(change, patchNum) {
       // Polymer 2: check for undefined
       if ([change, patchNum].some(arg => arg === undefined)) {
-        return undefined;
+        return [];
       }
 
       for (const rev of Object.values(change.revisions || {})) {

polygerrit-ui/app/elements/edit/gr-editor-view/gr-editor-view.js

@@ -216,7 +216,7 @@
         newContent,
         saving,
       ].some(arg => arg === undefined)) {
-        return undefined;
+        return true;
       }
 
       if (saving) {

polygerrit-ui/app/elements/shared/gr-editable-content/gr-editable-content.js

@@ -124,7 +124,7 @@
         content,
         newContent,
       ].some(arg => arg === undefined)) {
-        return undefined;
+        return true;
       }
 
       return disabled || (content === newContent);