Fix bad DartDoc in Set.toSet documentation.

Change-Id: I1801d4d8f3f25c76885f3482ae1553d32e6ee15b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/168828
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
diff --git a/pkg/dev_compiler/tool/dartdevc_nnbd_sdk_error_golden.txt b/pkg/dev_compiler/tool/dartdevc_nnbd_sdk_error_golden.txt
index 35dd9b3..39bf88b 100644
--- a/pkg/dev_compiler/tool/dartdevc_nnbd_sdk_error_golden.txt
+++ b/pkg/dev_compiler/tool/dartdevc_nnbd_sdk_error_golden.txt
@@ -1,11 +1,11 @@
 ERROR|COMPILE_TIME_ERROR|CONST_CONSTRUCTOR_THROWS_EXCEPTION|lib/core/core.dart|3679|5|94|Const constructors can't throw exceptions.
-ERROR|COMPILE_TIME_ERROR|CONST_CONSTRUCTOR_THROWS_EXCEPTION|lib/core/core.dart|7879|5|97|Const constructors can't throw exceptions.
+ERROR|COMPILE_TIME_ERROR|CONST_CONSTRUCTOR_THROWS_EXCEPTION|lib/core/core.dart|7880|5|97|Const constructors can't throw exceptions.
 ERROR|COMPILE_TIME_ERROR|CONST_CONSTRUCTOR_THROWS_EXCEPTION|lib/core/core.dart|893|5|95|Const constructors can't throw exceptions.
 ERROR|COMPILE_TIME_ERROR|CONST_CONSTRUCTOR_THROWS_EXCEPTION|lib/core/core.dart|926|5|94|Const constructors can't throw exceptions.
 ERROR|COMPILE_TIME_ERROR|INVALID_ASSIGNMENT|lib/_internal/js_dev_runtime/private/interceptors.dart|1358|18|27|A value of type 'double' can't be assigned to a variable of type 'int'.
 ERROR|COMPILE_TIME_ERROR|RETURN_OF_INVALID_TYPE|lib/_internal/js_dev_runtime/private/interceptors.dart|1225|14|38|A value of type 'double' can't be returned from method '%' because it has a return type of 'JSNumber'.
 ERROR|COMPILE_TIME_ERROR|RETURN_OF_INVALID_TYPE|lib/_internal/js_dev_runtime/private/interceptors.dart|1227|14|38|A value of type 'double' can't be returned from method '%' because it has a return type of 'JSNumber'.
 ERROR|SYNTACTIC_ERROR|CONST_FACTORY|lib/core/core.dart|3677|3|5|Only redirecting factory constructors can be declared to be 'const'.
-ERROR|SYNTACTIC_ERROR|CONST_FACTORY|lib/core/core.dart|7877|3|5|Only redirecting factory constructors can be declared to be 'const'.
+ERROR|SYNTACTIC_ERROR|CONST_FACTORY|lib/core/core.dart|7878|3|5|Only redirecting factory constructors can be declared to be 'const'.
 ERROR|SYNTACTIC_ERROR|CONST_FACTORY|lib/core/core.dart|891|3|5|Only redirecting factory constructors can be declared to be 'const'.
 ERROR|SYNTACTIC_ERROR|CONST_FACTORY|lib/core/core.dart|924|3|5|Only redirecting factory constructors can be declared to be 'const'.
diff --git a/sdk/lib/core/set.dart b/sdk/lib/core/set.dart
index ae1e381..6f47e07 100644
--- a/sdk/lib/core/set.dart
+++ b/sdk/lib/core/set.dart
@@ -253,7 +253,8 @@
    */
   void clear();
 
-  /* Creates a [Set] with the same elements and behavior as this `Set`.
+  /**
+   * Creates a [Set] with the same elements and behavior as this `Set`.
    *
    * The returned set behaves the same as this set
    * with regard to adding and removing elements.