Fix conversion of TextChanges to FileCodeEdits for new file (#24126)

src/services/textChanges.ts

@@ -719,7 +719,7 @@ namespace ts.textChanges {
 
         export function newFileChanges(oldFile: SourceFile, fileName: string, statements: ReadonlyArray<Statement>, newLineCharacter: string): FileTextChanges {
             const text = statements.map(s => getNonformattedText(s, oldFile, newLineCharacter).text).join(newLineCharacter);
-            return { fileName, textChanges: [createTextChange(createTextSpan(0, 0), text)] };
+            return { fileName, textChanges: [createTextChange(createTextSpan(0, 0), text)], isNewFile: true };
         }
 
         function computeNewText(change: Change, sourceFile: SourceFile, newLineCharacter: string, formatContext: formatting.FormatContext, validate: ValidateNonFormattedText): string {

src/services/types.ts

@@ -439,6 +439,7 @@ namespace ts {
     export interface FileTextChanges {
         fileName: string;
         textChanges: TextChange[];
+        isNewFile?: boolean;
     }
 
     export interface CodeAction {