Recognize unmodifiable lists

pkg/compiler/lib/src/ssa/codegen.dart

 // Copyright (c) 2012, 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.
 
 part of ssa;
 
 class SsaCodeGeneratorTask extends CompilerTask {
 
   final JavaScriptBackend backend;
   final SourceInformationFactory sourceInformationFactory;
@@ skipping 2314 matching lines @@
         checkExtendableArray(input);
       }
       return;
     } else if (element == backend.jsFixedArrayClass) {
       if (negative) {
         checkExtendableArray(input);
       } else {
         checkFixedArray(input);
       }
       return;
+    } else if (element == backend.jsUnmodifiableArrayClass) {
+      if (negative) {
+        checkMutableArray(input);
+      } else {
+        checkImmutableArray(input);
+      }
+      return;
     }
     if (interceptor != null) {
       checkTypeViaProperty(interceptor, type, negative);
     } else {
       checkTypeViaProperty(input, type, negative);
     }
   }
 
   void checkTypeViaProperty(HInstruction input, DartType type, bool negative) {
     registry.registerIsCheck(type);
@@ skipping 373 matching lines @@
   js.PropertyAccess accessHelper(String name) {
     Element helper = backend.findHelper(name);
     if (helper == null) {
       // For mocked-up tests.
       return js.js('(void 0).$name');
     }
     registry.registerStaticUse(helper);
     return backend.emitter.staticFunctionAccess(helper);
   }
 }