Recognize unmodifiable lists

pkg/compiler/lib/src/ssa/nodes.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;
 
 abstract class HVisitor<R> {
   R visitAdd(HAdd node);
   R visitAwait(HAwait node);
   R visitBitAnd(HBitAnd node);
@@ skipping 882 matching lines @@
     ClassWorld classWorld = compiler.world;
     JavaScriptBackend backend = compiler.backend;
     return instructionType.contains(backend.jsBoolClass, classWorld);
   }
 
   bool canBePrimitiveArray(Compiler compiler) {
     ClassWorld classWorld = compiler.world;
     JavaScriptBackend backend = compiler.backend;
     return instructionType.contains(backend.jsArrayClass, classWorld)
         || instructionType.contains(backend.jsFixedArrayClass, classWorld)
-        || instructionType.contains(backend.jsExtendableArrayClass, classWorld);
+        || instructionType.contains(backend.jsExtendableArrayClass, classWorld)
+        || instructionType.contains(
+            backend.jsUnmodifiableArrayClass, classWorld);
   }
 
   bool isIndexablePrimitive(Compiler compiler) {
     ClassWorld classWorld = compiler.world;
     JavaScriptBackend backend = compiler.backend;
     return instructionType.containsOnlyString(classWorld)
         || instructionType.satisfies(backend.jsIndexableClass, classWorld);
   }
 
   bool isFixedArray(Compiler compiler) {
     JavaScriptBackend backend = compiler.backend;
-    return instructionType.containsOnly(backend.jsFixedArrayClass);
+    // TODO(sra): Recognize the union of these types as well.
+    return instructionType.containsOnly(backend.jsFixedArrayClass)
+        || instructionType.containsOnly(backend.jsUnmodifiableArrayClass);
   }
 
   bool isExtendableArray(Compiler compiler) {
     JavaScriptBackend backend = compiler.backend;
     return instructionType.containsOnly(backend.jsExtendableArrayClass);
   }
 
   bool isMutableArray(Compiler compiler) {
     ClassWorld classWorld = compiler.world;
     JavaScriptBackend backend = compiler.backend;
@@ skipping 2251 matching lines @@
 class HDynamicType extends HRuntimeType {
   HDynamicType(DynamicType dartType, TypeMask instructionType)
       : super(const <HInstruction>[], dartType, instructionType);
 
   accept(HVisitor visitor) => visitor.visitDynamicType(this);
 
   int typeCode() => HInstruction.DYNAMIC_TYPE_TYPECODE;
 
   bool typeEquals(HInstruction other) => other is HDynamicType;
 }