Support if-statements in analyzer2dart.

pkg/analyzer2dart/lib/src/cps_generator.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 analyzer2dart.cps_generator;
 
 import 'package:analyzer/analyzer.dart';
 
 import 'package:compiler/implementation/elements/elements.dart' as dart2js;
 import 'package:analyzer/src/generated/source.dart';
@@ skipping 203 matching lines @@
     switch (op) {
     case '||':
     case '&&':
       return handleLazyOperator(node, isLazyOr: op == '||');
     case '!=':
       return irBuilder.buildNegation(handleBinaryExpression(node, '=='));
     default:
       return handleBinaryExpression(node, op);
     }
   }
+
+  @override
+  visitIfStatement(IfStatement node) {
+    ir.Primitive condition = node.condition.accept(this);
+
+    void buildThenPart(IrBuilder thenBuilder) {
+      withBuilder(thenBuilder, () => node.thenStatement.accept(this));
+    }
+
+    void buildElsePart(IrBuilder elseBuilder) {
+      if (node.elseStatement != null) {
+        withBuilder(elseBuilder, () => node.elseStatement.accept(this));
+      }
+    }
+
+    irBuilder.buildIf(condition, buildThenPart, buildElsePart);
+  }
 }