Fixes microsoft#31629 and removes duplicate comments on refactors

Author: orta

src/services/refactors/extractType.ts

@@ -160,7 +160,8 @@ namespace ts.refactor {
             selection
         );
         changes.insertNodeBefore(file, firstStatement, ignoreSourceNewlines(newTypeNode), /* blankLineBetween */ true);
-        changes.replaceNode(file, selection, createTypeReferenceNode(name, typeParameters.map(id => createTypeReferenceNode(id.name, /* typeArguments */ undefined))));
+        changes.replaceNode(file, selection, createTypeReferenceNode(name, typeParameters.map(id => createTypeReferenceNode(id.name, /* typeArguments */ undefined))), { trailingTriviaOption: textChanges.TrailingTriviaOption.Include });
+
     }
 
     function doInterfaceChange(changes: textChanges.ChangeTracker, file: SourceFile, name: string, info: InterfaceInfo) {

tests/cases/fourslash/refactorExtractType69.ts

@@ -0,0 +1,16 @@
+/// <reference path='fourslash.ts' />
+/// Doesn't duplicate comments - #31629
+
+//// type a = /*a*/{ x: string } /* foo */ | string /* bar */ /*b*/;
+
+goTo.select("a", "b");
+edit.applyRefactor({
+  refactorName: "Extract type",
+  actionName: "Extract to type alias",
+  actionDescription: "Extract to type alias",
+  newContent: `type /*RENAME*/NewType = {
+    x: string;
+} /* foo */ | string /* bar */;
+
+type a = NewType;`,
+});