Fixes #9521 (#9530)

* Fixes #9521

* Another test

* Update load-file-loader-a-lot.test.ts

* Update module_loader.zig

* comments

* Rename variable

* Update module_loader.zig

* Update exports.zig

* small cleanup

* bundows

---------

Co-authored-by: Jarred Sumner <709451+Jarred-Sumner@users.noreply.github.com>

src/string.zig

@@ -308,6 +308,16 @@ pub const String = extern struct {
         }
     }
 
+    pub fn createIfDifferent(other: String, utf8_slice: []const u8) String {
+        if (other.tag == .WTFStringImpl) {
+            if (other.eqlUTF8(utf8_slice)) {
+                return other.dupeRef();
+            }
+        }
+
+        return createUTF8(utf8_slice);
+    }
+
     fn createUninitializedLatin1(len: usize) struct { String, []u8 } {
         std.debug.assert(len > 0);
         const string = BunString__fromLatin1Unitialized(len);