Avoid inlining constants that are used via a deferred import.

sdk/lib/_internal/compiler/implementation/constants.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 dart2js;
 
 abstract class ConstantVisitor<R> {
   R visitFunction(FunctionConstant constant);
   R visitNull(NullConstant constant);
   R visitInt(IntConstant constant);
   R visitDouble(DoubleConstant constant);
   R visitTrue(TrueConstant constant);
   R visitFalse(FalseConstant constant);
   R visitString(StringConstant constant);
   R visitList(ListConstant constant);
   R visitMap(MapConstant constant);
   R visitConstructed(ConstructedConstant constant);
   R visitType(TypeConstant constant);
   R visitInterceptor(InterceptorConstant constant);
   R visitDummy(DummyConstant constant);
+  R visitDeferred(DeferredConstant constant);
 }
 
 abstract class Constant {
   const Constant();
 
   bool get isNull => false;
   bool get isBool => false;
   bool get isTrue => false;
   bool get isFalse => false;
   bool get isInt => false;
@@ skipping 614 matching lines @@
       if (i > 0) sb.write(',');
       sb.write(Error.safeToString(field.name));
       sb.write('=');
       sb.write(Error.safeToString(value));
       i++;
     });
     sb.write('))');
     return sb.toString();
   }
 }
+
+/// A reference to a constant in another output unit.
+/// Used for referring to deferred constants.
+class DeferredConstant extends Constant {
+  DeferredConstant(this.referenced, this.prefix);
+
+  final Constant referenced;
+  final PrefixElement prefix;
+
+  bool get isReference => true;
+
+  bool operator ==(other) {
+    return other is DeferredConstant
+        && referenced == other.referenced
+        && prefix == other.prefix;
+  }
+
+  get hashCode => (referenced.hashCode * 17 + prefix.hashCode) & 0x3fffffff;
+
+  List<Constant> getDependencies() => <Constant>[referenced];
+
+  accept(ConstantVisitor visitor) => visitor.visitDeferred(this);
+
+  DartType computeType(Compiler compiler) => referenced.computeType(compiler);
+
+  ti.TypeMask computeMask(Compiler compiler) {
+    return referenced.computeMask(compiler);
+  }
+
+  String toString() {
+    return 'DeferredConstant($referenced)';
+  }
+}