Support top-level field declaration and assignment in analyzer2dart.

pkg/compiler/lib/src/tree_ir/tree_ir_builder.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 tree_ir_builder;
 
 import '../dart2jslib.dart' as dart2js;
 import '../dart_types.dart';
 import '../elements/elements.dart';
 import '../cps_ir/cps_ir_nodes.dart' as cps_ir;
@@ skipping 108 matching lines @@
   ExecutableDefinition build(cps_ir.ExecutableDefinition node) {
     if (node is cps_ir.FieldDefinition) {
       return buildField(node);
     } else if (node is cps_ir.FunctionDefinition) {
       return buildFunction(node);
     }
     assert(false);
   }
 
   FieldDefinition buildField(cps_ir.FieldDefinition node) {
-    currentElement = node.element;
-    returnContinuation = node.returnContinuation;
+    Statement body;
+    if (node.hasInitializer) {
+      currentElement = node.element;
+      returnContinuation = node.returnContinuation;
 
-    phiTempVar = new Variable(node.element, null);
+      phiTempVar = new Variable(node.element, null);
 
-    return new FieldDefinition(node.element, visit(node.body));
+      body = visit(node.body);
+    }
+    return new FieldDefinition(node.element, body);
   }
 
   FunctionDefinition buildFunction(cps_ir.FunctionDefinition node) {
     currentElement = node.element;
     List<Variable> parameters = <Variable>[];
     for (cps_ir.Parameter p in node.parameters) {
       Variable parameter = getVariable(p);
       assert(parameter != null);
       ++parameter.writeCount; // Being a parameter counts as a write.
       parameters.add(parameter);
@@ skipping 351 matching lines @@
 
   Expression visitIdentical(cps_ir.Identical node) {
     return new InvokeStatic(
         compiler.identicalFunction,
         identicalSelector,
         <Expression>[getVariableReference(node.left),
                      getVariableReference(node.right)]);
   }
 }