Let CSP-mode-flag be available as a foreign_helper constant.

sdk/lib/_internal/compiler/js_lib/js_mirrors.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart._js_mirrors;
 
 import 'dart:_js_embedded_names' show
     JsGetName,
     ALL_CLASSES,
     LAZIES,
     LIBRARIES,
     STATICS,
     TYPE_INFORMATION,
     TYPEDEF_PREDICATE_PROPERTY_NAME,
     TYPEDEF_TYPE_PROPERTY_NAME;
 
 import 'dart:collection' show
     UnmodifiableListView,
     UnmodifiableMapView;
 
 import 'dart:mirrors';
 
 import 'dart:_foreign_helper' show
     JS,
+    JS_GET_FLAG,
     JS_CURRENT_ISOLATE,
     JS_CURRENT_ISOLATE_CONTEXT,
     JS_EMBEDDED_GLOBAL,
     JS_GET_NAME,
     JS_TYPEDEF_TAG,
     JS_FUNCTION_TYPE_TAG,
     JS_FUNCTION_TYPE_RETURN_TYPE_TAG,
     JS_FUNCTION_TYPE_VOID_RETURN_TAG,
     JS_FUNCTION_TYPE_REQUIRED_PARAMETERS_TAG,
     JS_FUNCTION_TYPE_OPTIONAL_PARAMETERS_TAG,
@@ skipping 1048 matching lines @@
   }
 
   // JS helpers for getField optimizations.
   static bool isUndefined(x)
       => JS('bool', 'typeof # == "undefined"', x);
   static bool isMissingCache(x)
       => JS('bool', 'typeof # == "number"', x);
   static bool isMissingProbe(Symbol symbol)
       => JS('bool', 'typeof #.\$p == "undefined"', symbol);
   static bool isEvalAllowed()
-      => JS('bool', 'typeof dart_precompiled != "function"');
+      => !JS_GET_FLAG("USE_CONTENT_SECURITY_POLICY");
 
 
   /// The getter cache is lazily allocated after a couple
   /// of invocations of [InstanceMirror.getField]. The delay is
   /// used to avoid too aggressive caching and dynamic function
   /// generation for rarely used mirrors. The cache is specific to
   /// this [InstanceMirror] and maps reflective names to functions
   /// that will invoke the corresponding getter on the reflectee.
   /// The reflectee is passed to the function as the first argument
   /// to avoid the overhead of fetching it from this mirror repeatedly.
@@ skipping 1933 matching lines @@
   // have a part (following a '.') that starts with '_'.
   const int UNDERSCORE = 0x5f;
   if (name.isEmpty) return true;
   int index = -1;
   do {
     if (name.codeUnitAt(index + 1) == UNDERSCORE) return false;
     index = name.indexOf('.', index + 1);
   } while (index >= 0 && index + 1 < name.length);
   return true;
 }