Skip spurious constants in deferred computation.

pkg/compiler/lib/src/js_backend/constant_handler_javascript.dart

 // Copyright (c) 2014, 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 js_backend;
 
 /// [ConstantCompilerTask] for compilation of constants for the JavaScript
 /// backend.
 ///
 /// Since this task needs to distinguish between frontend and backend constants
 /// the actual compilation of the constants is forwarded to a
 /// [DartConstantCompiler] for the frontend interpretation of the constants and
 /// to a [JavaScriptConstantCompiler] for the backend interpretation.
 class JavaScriptConstantTask extends ConstantCompilerTask {
   DartConstantCompiler dartConstantCompiler;
   JavaScriptConstantCompiler jsConstantCompiler;
 
   JavaScriptConstantTask(Compiler compiler)
       : this.dartConstantCompiler = new DartConstantCompiler(compiler),
         this.jsConstantCompiler = new JavaScriptConstantCompiler(compiler),
         super(compiler);
 
   String get name => 'ConstantHandler';
 
   @override
   ConstantSystem get constantSystem => dartConstantCompiler.constantSystem;
 
   @override
+  bool hasConstantValue(ConstantExpression expression) {
+    return dartConstantCompiler.hasConstantValue(expression);
+  }
+
+  @override
   ConstantValue getConstantValue(ConstantExpression expression) {
     return dartConstantCompiler.getConstantValue(expression);
   }
 
   @override
   ConstantValue getConstantValueForVariable(VariableElement element) {
     return dartConstantCompiler.getConstantValueForVariable(element);
   }
 
   @override
@@ skipping 205 matching lines @@
       element.node.accept(new ForgetConstantNodeVisitor(this));
     }
   }
 
   @override
   ConstantValue getConstantValue(ConstantExpression expression) {
     assert(invariant(CURRENT_ELEMENT_SPANNABLE, expression != null,
         message: "ConstantExpression is null in getConstantValue."));
     // TODO(johhniwinther): ensure expressions have been evaluated at this
     // point. This can't be enabled today due to dartbug.com/26406.
-
+    if (compiler.serialization.supportsDeserialization) {
+      evaluate(expression);
+    }
     ConstantValue value = super.getConstantValue(expression);
     if (value == null &&
         expression != null &&
         expression.kind == ConstantExpressionKind.ERRONEOUS) {
       // TODO(johnniwinther): When the Dart constant system sees a constant
       // expression as erroneous but the JavaScript constant system finds it ok
       // we have store a constant value for the erroneous constant expression.
       // Ensure the computed constant expressions are always the same; that only
       // the constant values may be different.
       value = new NullConstantValue();
@@ skipping 36 matching lines @@
     // TODO(ahe): This doesn't belong here. Rename this class and generalize.
     var closureClassMap = constants
         .compiler.closureToClassMapper.closureMappingCache
         .remove(node);
     if (closureClassMap != null) {
       closureClassMap
           .removeMyselfFrom(constants.compiler.enqueuer.codegen.universe);
     }
   }
 }