fix #29789, avoid unneccessary dcalls and checks in dart:_runtime

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/operations.dart

Index: pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/operations.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/operations.dart b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/operations.dart
index ef7f3a94cfa7907a3d2ac358254626479f9a58c0..ea3ef3a1b8857b872b93738787d6893d271620cd 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/operations.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/operations.dart
@@ -1006,8 +1006,8 @@ _canonicalMember(obj, name) {
   }
 
   // Check for certain names that we can't use in JS
-  if (name == 'constructor' || name == 'prototype') {
-    name = '+' + name;
+  if (JS('bool', '# == "constructor" || # == "prototype"', name, name)) {
+    JS('', '# = "+" + #', name, name);
   }
   return name;
 }