Fixes VSCode highlighting of num.dart.

Closing backticks were required.

Closes #36146
https://github.com/dart-lang/sdk/pull/36146

GitOrigin-RevId: db9e112e92ec7de1c3f8e7ebb8e6171391853dd6
Change-Id: Idfdc28c99037bcad808dd70084057b0adf7adc6a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/95983
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
diff --git a/sdk/lib/core/num.dart b/sdk/lib/core/num.dart
index afad926..33b8177 100644
--- a/sdk/lib/core/num.dart
+++ b/sdk/lib/core/num.dart
@@ -100,6 +100,7 @@
    * print(double.infinity < double.nan);  // => false
    * print(double.nan < double.infinity);  // => false
    * print(double.nan == double.infinity);  // => false
+   * ```
    */
   int compareTo(num other);