Compute frontend/backend specific constants.

sdk/lib/_internal/compiler/implementation/dart_backend/backend.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 dart_backend;
 
 // TODO(ahe): This class is simply wrong.  This backend should use
 // elements when it can, not AST nodes.  Perhaps a [Map<Element,
 // TreeElements>] is what is needed.
 class ElementAst {
@@ skipping 27 matching lines @@
   /// Initialized when dart:mirrors is loaded if the useMirrorHelperLibrary
   /// field is set.
   FunctionElement mirrorHelperGetNameFunction;
   /// Initialized when dart:mirrors is loaded if the useMirrorHelperLibrary
   /// field is set.
   Element mirrorHelperSymbolsMap;
 
   Map<Element, TreeElements> get resolvedElements =>
       compiler.enqueuer.resolution.resolvedElements;
 
+  ConstantSystem get constantSystem {
+    return constantCompiler.constantCompiler.constantSystem;
+  }
+
+  BackendConstantHandler get constantHandler => constantCompiler;
+
+  DartConstantHandler constantCompiler;
+
   /**
    * Tells whether it is safe to remove type declarations from variables,
    * functions parameters. It becomes not safe if:
    * 1) TypeError is used somewhere in the code,
    * 2) The code has typedefs in right hand side of IS checks,
    * 3) The code has classes which extend typedefs, have type arguments typedefs
    *    or type variable bounds typedefs.
    * These restrictions can be less strict.
    */
   bool isSafeToRemoveTypeDeclarations(
@@ skipping 31 matching lines @@
   }
 
   DartBackend(Compiler compiler, List<String> strips)
       : tasks = <CompilerTask>[],
         renames = new Map<Node, String>(),
         imports = new Map<LibraryElement, String>(),
         memberNodes = new Map<ClassNode, List<Node>>(),
         reexportingLibraries = <Element, LibraryElement>{},
         forceStripTypes = strips.indexOf('types') != -1,
         stripAsserts = strips.indexOf('asserts') != -1,
+        constantCompiler = new DartConstantHandler(compiler),
         super(compiler);
 
   bool classNeedsRti(ClassElement cls) => false;
   bool methodNeedsRti(FunctionElement function) => false;
 
   void enqueueHelpers(ResolutionEnqueuer world, TreeElements elements) {
     // Right now resolver doesn't always resolve interfaces needed
     // for literals, so force them. TODO(antonm): fix in the resolver.
     final LITERAL_TYPE_NAMES = const [
       'Map', 'List', 'num', 'int', 'double', 'bool'
@@ skipping 440 matching lines @@
 }
 
 compareElements(e0, e1) {
   int result = compareBy((e) => e.getLibrary().canonicalUri.toString())(e0, e1);
   if (result != 0) return result;
   return compareBy((e) => e.position().charOffset)(e0, e1);
 }
 
 List<Element> sortElements(Iterable<Element> elements) =>
     sorted(elements, compareElements);