Generative constructors in the new dart backend.

pkg/compiler/lib/src/dart_backend/backend_ast_nodes.dart

Index: pkg/compiler/lib/src/dart_backend/backend_ast_nodes.dart
diff --git a/pkg/compiler/lib/src/dart_backend/backend_ast_nodes.dart b/pkg/compiler/lib/src/dart_backend/backend_ast_nodes.dart
index 2d113ed8476132cfa073a156d2fc31f58702b416..f9292a555c652c201ded9b12d7ed1fdb457bcdd4 100644
--- a/pkg/compiler/lib/src/dart_backend/backend_ast_nodes.dart
+++ b/pkg/compiler/lib/src/dart_backend/backend_ast_nodes.dart
@@ -306,6 +306,22 @@ class Parameter extends Node {
 
 // EXPRESSIONS
 
+abstract class Initializer extends Expression {}
+
+class FieldInitializer extends Initializer {
+  final elements.FieldElement element;
+  final Expression body;
+
+  FieldInitializer(this.element, this.body);
+}
+
+class SuperInitializer extends Initializer {
+  final elements.ConstructorElement target;
+  final List<Argument> arguments;
+
+  SuperInitializer(this.target, this.arguments);
+}
+
 class FunctionExpression extends Expression implements ExecutableDefinition {
   final TypeAnnotation returnType;
   String name;
@@ -327,6 +343,15 @@ class FunctionExpression extends Expression implements ExecutableDefinition {
   }
 }
 
+class ConstructorDefinition extends FunctionExpression {
+  final List<Initializer> initializers;
+  final bool isConst;
+
+  ConstructorDefinition(Parameters parameters, Statement body,
+                        this.initializers, String name, this.isConst)
+      : super(parameters, body, name: name);
+}
+
 class Conditional extends Expression {
   final Expression condition;
   final Expression thenExpression;