Make some VM libraries patch cleanly using the analyzer.

sdk/lib/_internal/js_runtime/lib/internal_patch.dart

Index: sdk/lib/_internal/js_runtime/lib/internal_patch.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/internal_patch.dart b/sdk/lib/_internal/js_runtime/lib/internal_patch.dart
index a0c519f89911b2dc39b6f7c479a96888dd8b8529..8fc8acfc33678946174901fac8f8fdac68c669fb 100644
--- a/sdk/lib/_internal/js_runtime/lib/internal_patch.dart
+++ b/sdk/lib/_internal/js_runtime/lib/internal_patch.dart
@@ -22,6 +22,9 @@ class Symbol implements core.Symbol {
     JS('', '#._hashCode = #', this, hash);
     return hash;
   }
+
+  @patch
+  toString() => 'Symbol("$_name")';
 }
 
 @patch