Use memory source files in compile_from_dill*

tests/compiler/dart2js/kernel/compiler_helper.dart

 // Copyright (c) 2017, 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.
 
 // Partial test that the closed world computed from [WorldImpact]s derived from
 // kernel is equivalent to the original computed from resolution.
 library dart2js.kernel.compiler_helper;
 
 import 'dart:async';
 import 'dart:io';
@@ skipping 119 matching lines @@
       compiler.backend.kernelTask.program);
   await compiler2.run(entryPoint);
   return new Pair<Compiler, Compiler>(compiler, compiler2);
 }
 
 class MemoryKernelLibraryLoaderTask extends KernelLibraryLoaderTask {
   final ir.Program program;
 
   MemoryKernelLibraryLoaderTask(KernelToElementMapForImpact elementMap,
       DiagnosticReporter reporter, Measurer measurer, this.program)
-      : super(null, elementMap, null, reporter, measurer);
+      : super(null, null, elementMap, null, reporter, measurer);
 
   Future<LoadedLibraries> loadLibrary(Uri resolvedUri,
       {bool skipFileWithPartOfTag: false}) async {
     return createLoadedLibraries(program);
   }
 }
 
 Future createTemp(Uri entryPoint, Map<String, String> memorySourceFiles,
     {bool printSteps: false}) async {
   if (memorySourceFiles.isNotEmpty) {
@@ skipping 30 matching lines @@
 }
 
 Future<Compiler> compileWithDill(
     {Uri entryPoint,
     Map<String, String> memorySourceFiles: const <String, String>{},
     List<String> options: const <String>[],
     CompilerDiagnostics diagnosticHandler,
     bool printSteps: false,
     CompilerOutput compilerOutput,
     void beforeRun(Compiler compiler)}) async {
-  Uri dillFile =
-      await generateDill(entryPoint, memorySourceFiles, printSteps: printSteps);
-
   if (printSteps) {
-    print('---- compile from dill $dillFile ---------------------------------');
+    print('---- compile from dill -------------------------------------------');
   }
   Compiler compiler = compilerFor(
-      entryPoint: dillFile,
+      entryPoint: entryPoint,
+      memorySourceFiles: memorySourceFiles,
       options: [Flags.useKernel]..addAll(options),
       diagnosticHandler: diagnosticHandler,
       outputProvider: compilerOutput);
   ElementResolutionWorldBuilder.useInstantiationMap = true;
   compiler.resolution.retainCachesForTesting = true;
   if (beforeRun != null) {
     beforeRun(compiler);
   }
-  await compiler.run(dillFile);
+  await compiler.run(entryPoint);
   return compiler;
 }