Avoid double iteration in preserveCommentsOn

Author: Andarist

src/compiler/checker.ts

@@ -7310,9 +7310,9 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             typeElements.push(preserveCommentsOn(propertySignature));
 
             function preserveCommentsOn<T extends Node>(node: T) {
-                if (some(propertySymbol.declarations, d => d.kind === SyntaxKind.JSDocPropertyTag)) {
-                    const d = propertySymbol.declarations?.find(d => d.kind === SyntaxKind.JSDocPropertyTag)! as JSDocPropertyTag;
-                    const commentText = getTextOfJSDocComment(d.comment);
+                const jsdocPropertyTag = propertySymbol.declarations?.find((d): d is JSDocPropertyTag => d.kind === SyntaxKind.JSDocPropertyTag);
+                if (jsdocPropertyTag) {
+                    const commentText = getTextOfJSDocComment(jsdocPropertyTag.comment);
                     if (commentText) {
                         setSyntheticLeadingComments(node, [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "*\n * " + commentText.replace(/\n/g, "\n * ") + "\n ", pos: -1, end: -1, hasTrailingNewLine: true }]);
                     }