Add IR nodes needed for deferred loading.

runtime/vm/kernel_binary.cc

Index: runtime/vm/kernel_binary.cc
diff --git a/runtime/vm/kernel_binary.cc b/runtime/vm/kernel_binary.cc
index 1f56c09be4e28396926cbec1b9673725f9df2d19..49ea7a0fcd90420d0c4b4feb165f380ec48b7016 100644
--- a/runtime/vm/kernel_binary.cc
+++ b/runtime/vm/kernel_binary.cc
@@ -644,6 +644,10 @@ Library* Library::ReadFrom(Reader* reader) {
   source_uri_index_ = reader->ReadUInt();
   reader->set_current_script_id(source_uri_index_);
 
+  int num_imports = reader->ReadUInt();
+  if (num_imports != 0) {
+    FATAL("Deferred imports not implemented in VM");
+  }
   int num_classes = reader->ReadUInt();
   classes().EnsureInitialized(num_classes);
   for (int i = 0; i < num_classes; i++) {