Add IR nodes needed for deferred loading.

pkg/kernel/lib/text/ast_to_text.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 library kernel.ast_to_text;
 
 import '../ast.dart';
 import '../import_table.dart';
 import '../type_propagation/type_propagation.dart';
 
 class Namer<T> {
@@ skipping 284 matching lines @@
       var importPath = imports.getImportPath(library);
       if (importPath == "") {
         var prefix =
             syntheticNames.nameLibraryPrefix(library, proposedName: 'self');
         endLine('import self as $prefix;');
       } else {
         var prefix = syntheticNames.nameLibraryPrefix(library);
         endLine('import "$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);
     library.fields.forEach(inner.writeNode);
     library.procedures.forEach(inner.writeNode);
   }
 
   void writeProgramFile(Program program) {
     ImportTable imports = new ProgramImportTable(program);
     var inner = new Printer._inner(this, imports);
@@ skipping 663 matching lines @@
     writeWord('null');
   }
 
   visitLet(Let node) {
     writeWord('let');
     writeVariableDeclaration(node.variable);
     writeSpaced('in');
     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}');
   }
 
   visitVariableGet(VariableGet node) {
     writeVariableReference(node.variable);
     if (node.promotedType != null) {
       writeSymbol('{');
       writeNode(node.promotedType);
       writeSymbol('}');
@@ skipping 555 matching lines @@
   }
   throw 'illegal ProcedureKind: $kind';
 }
 
 class ExpressionPrinter {
   final Printer writeer;
   final int minimumPrecedence;
 
   ExpressionPrinter(this.writeer, this.minimumPrecedence);
 }