Add support for not generating a .dill file.

lib/src/rastask.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.md file.
 
 library rasta.rastask;
 
 import 'dart:async' show
     Future;
 
 import 'dart:io' show
@@ skipping 100 matching lines @@
 
     Iterable<ir.Procedure> mainMethods = library.procedures.where(
         (ir.Procedure function) => function.name.name == "main");
     ir.Program program =
         new ir.Program(kernel.libraryDependencies(options.input));
 
     if (mainMethods.isNotEmpty) {
       program.mainMethod = mainMethods.single;
     }
     compiler.printVerboseTimings(setupDuration);
-    if (options.output != null) {
-      await openWrite(options.output, (IOSink sink) {
-        BinaryPrinter printer = new BinaryPrinter(sink);
-        printer.writeProgramFile(program);
-      });
-    } else {
-      StringBuffer buffer = new StringBuffer();
-      Printer printer = new Printer(buffer);
-      if (generateLibrary) {
-        printer.writeLibraryFile(library);
+    if (!options.noOutput) {
+      if (options.output != null) {
+        await openWrite(options.output, (IOSink sink) {
+          BinaryPrinter printer = new BinaryPrinter(sink);
+          printer.writeProgramFile(program);
+        });
       } else {
-        printer.writeProgramFile(program);
+        StringBuffer buffer = new StringBuffer();
+        Printer printer = new Printer(buffer);
+        if (generateLibrary) {
+          printer.writeLibraryFile(library);
+        } else {
+          printer.writeProgramFile(program);
+        }
+        print("$buffer");
       }
-      print("$buffer");
     }
 
     if (options.dependenciesFile != null) {
       await openWrite(options.dependenciesFile, (IOSink sink) {
         void writeCompilationUnit(CompilationUnitElement unit) {
           sink.write("${unit.script.resourceUri}\n");
         }
         kernel.forEachLibraryElement((LibraryElement library) {
           library.compilationUnits.forEach(writeCompilationUnit);
         });
@@ skipping 39 matching lines @@
     Rastask task;
     if (options.isBatch) {
       task = new RunBatch(compiler, wallClock, options);
     } else {
       task = new RunSingle(compiler, wallClock, options);
     }
     compiler.tasks.add(task);
     return task;
   }
 }