Add ConstantConstructor to ConstantExpression system.

pkg/compiler/lib/src/resolution/members.dart

Index: pkg/compiler/lib/src/resolution/members.dart
diff --git a/pkg/compiler/lib/src/resolution/members.dart b/pkg/compiler/lib/src/resolution/members.dart
index 22b8461ef349a4ab6ab54b7bc295341d52c0495b..fec856976ef4397b8ad47bdea3db80989a27bf64 100644
--- a/pkg/compiler/lib/src/resolution/members.dart
+++ b/pkg/compiler/lib/src/resolution/members.dart
@@ -714,7 +714,7 @@ class ResolverTask extends CompilerTask {
     if (Elements.isStaticOrTopLevelField(element)) {
       visitor.addDeferredAction(element, () {
         if (element.modifiers.isConst) {
-          constantCompiler.compileConstant(element);
+          element.constant = constantCompiler.compileConstant(element);
         } else {
           constantCompiler.compileVariable(element);
         }
@@ -2427,8 +2427,10 @@ class ResolverVisitor extends MappingVisitor<ResolutionResult> {
       parameterNodes = parameterNodes.tail;
     });
     addDeferredAction(enclosingElement, () {
-      functionParameters.forEachOptionalParameter((Element parameter) {
-        compiler.resolver.constantCompiler.compileConstant(parameter);
+      functionParameters.forEachOptionalParameter(
+          (ParameterElementX parameter) {
+        parameter.constant =
+            compiler.resolver.constantCompiler.compileConstant(parameter);
       });
     });
     if (inCheckContext) {
@@ -4869,14 +4871,15 @@ class VariableDefinitionsVisitor extends CommonResolverVisitor<Identifier> {
   visitNodeList(NodeList node) {
     for (Link<Node> link = node.nodes; !link.isEmpty; link = link.tail) {
       Identifier name = visit(link.head);
-      LocalVariableElement element = new LocalVariableElementX(
+      LocalVariableElementX element = new LocalVariableElementX(
           name.source, resolver.enclosingElement,
           variables, name.token);
       resolver.defineLocalVariable(link.head, element);
       resolver.addToScope(element);
       if (definitions.modifiers.isConst) {
         compiler.enqueuer.resolution.addDeferredAction(element, () {
-          compiler.resolver.constantCompiler.compileConstant(element);
+          element.constant =
+              compiler.resolver.constantCompiler.compileConstant(element);
         });
       }
     }