dart2js cps: Support sync* and yield.

pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart

Index: pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart
diff --git a/pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart b/pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart
index f6b6a729b36f3d31864fc673aec4fb35b86021e9..00487eee81c15cec6848bb8c4c47fe8870c67e86 100644
--- a/pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart
+++ b/pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart
@@ -1135,6 +1135,13 @@ class StatementRewriter extends Transformer implements Pass {
 
   @override
   Expression visitAwait(Await node) {
+    node.input = visitExpression(node.input);
+    return node;
+  }
+
+  @override
+  Statement visitYield(Yield node) {
+    node.input = visitExpression(node.input);
     return node;
   }
 }