Switch to checked-in binary of d8

tools/testing/dart/test_suite.dart

Index: tools/testing/dart/test_suite.dart
diff --git a/tools/testing/dart/test_suite.dart b/tools/testing/dart/test_suite.dart
index e888996786550c89ba56ad0a209ace3d88b4133a..ea8877b8f9cc5d212703a07467a9853be3b8ef3a 100644
--- a/tools/testing/dart/test_suite.dart
+++ b/tools/testing/dart/test_suite.dart
@@ -188,16 +188,6 @@ abstract class TestSuite {
     }
   }
 
-  /**
-   * The file name of the d8 executable.
-   */
-  String get d8FileName {
-    var suffix = getExecutableSuffix('d8');
-    var d8 = '$buildDir/d8$suffix';
-    TestUtils.ensureExists(d8, configuration);
-    return d8;
-  }
-
   String get dartShellFileName {
     var name = configuration['dart'];
     if (name == '') {
@@ -208,6 +198,14 @@ abstract class TestSuite {
     return name;
   }
 
+  String get d8FileName {
+    var suffix = getExecutableSuffix('d8');
+    var d8Dir = '${TestUtils.dartDir()}/third_party/d8';
+    var d8 = '$d8Dir/${Platform.operatingSystem}/d8$suffix';
+    TestUtils.ensureExists(d8, configuration);
+    return d8;
+  }
+
   String get jsShellFileName {
     var executableSuffix = getExecutableSuffix('jsshell');
     var executable = 'jsshell$executableSuffix';