GN Build fixes for Flutter + gen_snapshot fix

tools/testing/dart/compiler_configuration.dart

Index: tools/testing/dart/compiler_configuration.dart
diff --git a/tools/testing/dart/compiler_configuration.dart b/tools/testing/dart/compiler_configuration.dart
index 147cd993445f5759207f32ad6fd3056807b2e243..80d1fac9b2477c9efaf18d5484329081b4508b6c 100644
--- a/tools/testing/dart/compiler_configuration.dart
+++ b/tools/testing/dart/compiler_configuration.dart
@@ -4,7 +4,7 @@
 
 library compiler_configuration;
 
-import 'dart:io' show Platform;
+import 'dart:io' show Directory, Platform;
 
 import 'runtime_configuration.dart' show RuntimeConfiguration;
 
@@ -333,9 +333,23 @@ class PrecompilerCompilerConfiguration extends CompilerConfiguration {
       CommandBuilder commandBuilder,
       List arguments,
       Map<String, String> environmentOverrides) {
-    var exec = "$buildDir/dart_bootstrap";
+    var sourceDir = Directory.current.path;
+    var exec = "$buildDir/gen_snapshot";
     var args = new List();
-    args.add("--gen-precompiled-snapshot=$tempDir");
+
+    var precompiledVMIsolate = "$tempDir/precompiled.vmisolate";
+    var precompiledIsolate = "$tempDir/precompiled.isolate";
+    var precompiledInstructions = "$tempDir/precompiled.S";
+    var dartProductEntries = "$sourceDir/runtime/bin/dart_product_entries.txt";
+    var dartEntries = "$sourceDir/runtime/bin/dart_entries.txt";
+    var vmServiceIoMain = "$sourceDir/runtime/bin/vmservice/vmservice_io.dart";
+
+    args.add("--embedder_entry_points_manifest=$dartProductEntries");
+    args.add("--embedder_entry_points_manifest=$dartEntries");

[rmacnak, 2016/04/20 22:56:04]

if (!product) {
  args.add("--embedder_entry_points_manifest=$dartEntries");
}

[Cutch, 2016/04/21 15:00:56]

Done.

+    args.add("--vm_isolate_snapshot=$precompiledVMIsolate");
+    args.add("--isolate_snapshot=$precompiledIsolate");
+    args.add("--instructions_snapshot=$precompiledInstructions");
+    args.add("--url_mapping=dart:vmservice_io,$vmServiceIoMain");
     args.addAll(arguments);
 
     return commandBuilder.getCompilationCommand('precompiler', tempDir, !useSdk,