Support top-level field declaration and assignment in analyzer2dart.

pkg/compiler/lib/src/dart_backend/backend_ast_emitter.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.
 
 library backend_ast_emitter;
 
 import '../tree_ir/tree_ir_nodes.dart' as tree;
 import 'backend_ast_nodes.dart';
 import '../constants/expressions.dart';
 import '../constants/values.dart';
@@ skipping 182 matching lines @@
     if (definition is tree.FieldDefinition) {
       return emitField(definition, context);
     }
     assert(definition is tree.FunctionDefinition);
     return emitFunction(definition, context);
   }
 
   FieldDefinition emitField(tree.FieldDefinition definition,
                             BuilderContext<Statement> context) {
     context.currentElement = definition.element;
-    visitStatement(definition.body, context);
-    List<Statement> bodyParts;
-    for (tree.Variable variable in context.variableNames.keys) {
-      if (!context.declaredVariables.contains(variable)) {
-        context.addDeclaration(variable);
+    Expression initializer;
+    if (definition.hasInitializer) {
+      visitStatement(definition.body, context);
+      List<Statement> bodyParts;
+      for (tree.Variable variable in context.variableNames.keys) {
+        if (!context.declaredVariables.contains(variable)) {
+          context.addDeclaration(variable);
+        }
       }
-    }
-    if (context.variables.length > 0) {
-      bodyParts = new List<Statement>();
-      bodyParts.add(new VariableDeclarations(context.variables));
-      bodyParts.addAll(context.statements);
-    } else {
-      bodyParts = context.statements;
+      if (context.variables.length > 0) {
+        bodyParts = new List<Statement>();
+        bodyParts.add(new VariableDeclarations(context.variables));
+        bodyParts.addAll(context.statements);
+      } else {
+        bodyParts = context.statements;
+      }
+      initializer = ensureExpression(bodyParts);
     }
 
-    return new FieldDefinition(definition.element, ensureExpression(bodyParts));
+    return new FieldDefinition(definition.element, initializer);
   }
 
   /// Returns an expression that will evaluate all of [bodyParts].
   /// If [bodyParts] is a single [Return] return its value.
   /// Otherwise wrap the body-parts in an immediately invoked closure.
   Expression ensureExpression(List<Statement> bodyParts) {
     if (bodyParts.length == 1) {
       Statement onlyStatement = bodyParts.single;
       if (onlyStatement is Return) {
         return onlyStatement.expression;
@@ skipping 845 matching lines @@
       : super(name, ElementKind.VARIABLE, enclosingElement, variables, null);
 
   ExecutableElement get executableContext => enclosingElement;
 
   ExecutableElement get memberContext => executableContext.memberContext;
 
   bool get isLocal => true;
 
   LibraryElement get implementationLibrary => enclosingElement.library;
 }