Add primitive to create closures and use it for closure conversion

pkg/kernel/lib/binary/ast_to_binary.dart

Index: pkg/kernel/lib/binary/ast_to_binary.dart
diff --git a/pkg/kernel/lib/binary/ast_to_binary.dart b/pkg/kernel/lib/binary/ast_to_binary.dart
index 2c87df570979b7c95ebca030b559d3357531f6bd..5092e69294be5f81bc22c0af49e849557176e5f6 100644
--- a/pkg/kernel/lib/binary/ast_to_binary.dart
+++ b/pkg/kernel/lib/binary/ast_to_binary.dart
@@ -751,6 +751,13 @@ class BinaryPrinter extends Visitor {
     writeNode(node.vectorExpression);
   }
 
+  visitClosureCreation(ClosureCreation node) {
+    writeByte(Tag.ClosureCreation);
+    writeReference(node.topLevelFunctionReference);
+    writeNode(node.contextVector);
+    writeNode(node.functionType);
+  }
+
   writeStatementOrEmpty(Statement node) {
     if (node == null) {
       writeByte(Tag.EmptyStatement);