Support if-statements in analyzer2dart.

pkg/analyzer2dart/lib/src/cps_generator.dart

Index: pkg/analyzer2dart/lib/src/cps_generator.dart
diff --git a/pkg/analyzer2dart/lib/src/cps_generator.dart b/pkg/analyzer2dart/lib/src/cps_generator.dart
index 94c890d4c90b75c6808733d6c98e9a14c8348a10..c81513aec444dcd9c6952b0dfda90ead040c827b 100644
--- a/pkg/analyzer2dart/lib/src/cps_generator.dart
+++ b/pkg/analyzer2dart/lib/src/cps_generator.dart
@@ -221,4 +221,21 @@ class CpsGeneratingVisitor extends SemanticVisitor<ir.Node>
       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);
+  }
 }