Manually iterate

Author: jakebailey

src/compiler/core.ts

@@ -689,7 +689,10 @@ export function concatenate<T>(array1: readonly T[] | undefined, array2: readonl
 export function concatenate<T>(array1: readonly T[] | undefined, array2: readonly T[] | undefined): readonly T[] | undefined {
     if (array2 === undefined || array2.length === 0) return array1;
     if (array1 === undefined || array1.length === 0) return array2;
-    return array1.concat(array2);
+    const result: T[] = [];
+    for (let i = 0; i < array1.length; i++) result.push(array1[i]);
+    for (let i = 0; i < array2.length; i++) result.push(array2[i]);
+    return result;
 }
 
 function selectIndex(_: unknown, i: number) {