Add IR nodes needed for deferred loading.

pkg/kernel/lib/text/ast_to_text.dart

Index: pkg/kernel/lib/text/ast_to_text.dart
diff --git a/pkg/kernel/lib/text/ast_to_text.dart b/pkg/kernel/lib/text/ast_to_text.dart
index a0e722740c670be7aacd0a04f5999c75583fdc53..d8c892e3e0f50fb52dede9756196a4703a0205e9 100644
--- a/pkg/kernel/lib/text/ast_to_text.dart
+++ b/pkg/kernel/lib/text/ast_to_text.dart
@@ -302,6 +302,9 @@ class Printer extends Visitor<Null> {
         endLine('import "$importPath" as $prefix;');
       }
     }
+    for (var import in library.deferredImports) {
+      import.accept(this);
+    }
     endLine();
     var inner = new Printer._inner(this, imports);
     library.classes.forEach(inner.writeNode);
@@ -985,6 +988,30 @@ class Printer extends Visitor<Null> {
     writeExpression(node.body);
   }
 
+  visitLoadLibrary(LoadLibrary node) {
+    writeWord('LoadLibrary');
+    writeSymbol('(');
+    writeWord(node.import.name);
+    writeSymbol(')');
+    state = WORD;
+  }
+
+  visitCheckLibraryIsLoaded(CheckLibraryIsLoaded node) {
+    writeWord('CheckLibraryIsLoaded');
+    writeSymbol('(');
+    writeWord(node.import.name);
+    writeSymbol(')');
+    state = WORD;
+  }
+
+  visitDeferredImport(DeferredImport node) {
+    write('import "');
+    write('${node.importedLibrary.importUri}');
+    write('" deferred as ');
+    write(node.name);
+    endLine(';');
+  }
+
   defaultExpression(Expression node) {
     writeWord('${node.runtimeType}');
   }