P4TB-391: Follow-up to commit 56d9aee0 and commit 4c369760: Simplify code (replace loop with .includes()).

addon/content/pepmessengercompose.js

@@ -372,7 +372,6 @@ var pEpComposer = {
           let dotPos = name.lastIndexOf(".");
           let tryAppend = 1;
           let newName;
-          let found;
           do {
             tryAppend++;
             if (dotPos < 0) {
@@ -380,14 +379,7 @@ var pEpComposer = {
             } else {
               newName = `${name.substring(0, dotPos)}(${tryAppend})${name.substring(dotPos)}`;
             }
-            found = false;
-            for (let k = 0; k < rowCount; k++) {
-              if (newName == attachmentNames[k]) {
-                found = true;
-                break;
-              }
-            }
-          } while (found);
+          } while (attachmentNames.includes(newName));
 
           attachmentNames[j] = newName;
           let item = bucket.getItemAtIndex(j);

addon/content/pepmsghdrview.js

@@ -353,7 +353,6 @@ var pEpHdrView = {
           let dotPos = name.lastIndexOf(".");
           let tryAppend = 1;
           let newName;
-          let found;
           do {
             tryAppend++;
             if (dotPos < 0) {
@@ -361,14 +360,7 @@ var pEpHdrView = {
             } else {
               newName = `${name.substring(0, dotPos)}(${tryAppend})${name.substring(dotPos)}`;
             }
-            found = false;
-            for (let k = 0; k < attLength; k++) {
-              if (newName == attachmentNames[k]) {
-                found = true;
-                break;
-              }
-            }
-          } while (found);
+          } while (attachmentNames.includes(newName));
 
           attachmentNames[j] = newName;
           this.win.currentAttachments[j].name = newName;