Fix cctest + unittest to work with an external snapshot.

test/unittests/run-all-unittests.cc

Index: test/unittests/run-all-unittests.cc
diff --git a/test/unittests/run-all-unittests.cc b/test/unittests/run-all-unittests.cc
index 8c361ddc3683eeb4af4f432b1454f540de41fbf9..d2cc7dd77eafba3efd35255cf7c6772ff2d9a35c 100644
--- a/test/unittests/run-all-unittests.cc
+++ b/test/unittests/run-all-unittests.cc
@@ -7,6 +7,10 @@
 #include "src/base/compiler-specific.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
+#ifdef V8_USE_EXTERNAL_STARTUP_DATA
+#include "src/startup-data-util.h"
+#endif  // V8_USE_EXTERNAL_STARTUP_DATA
+
 namespace {
 
 class DefaultPlatformEnvironment FINAL : public ::testing::Environment {
@@ -41,5 +45,8 @@ int main(int argc, char** argv) {
   testing::InitGoogleMock(&argc, argv);
   testing::AddGlobalTestEnvironment(new DefaultPlatformEnvironment);
   v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
+#ifdef V8_USE_EXTERNAL_STARTUP_DATA
+  v8::StartupDataHandler startup_data(argv[0], NULL, NULL);
+#endif
   return RUN_ALL_TESTS();
 }