Fix http://dartbug.com/23578:

runtime/bin/main.cc

Index: runtime/bin/main.cc
diff --git a/runtime/bin/main.cc b/runtime/bin/main.cc
index d1e80d6e7a1f55e2560ac060da87df5559018ea0..bb014029b5587482b5d65edf9cc8e486069e3304 100644
--- a/runtime/bin/main.cc
+++ b/runtime/bin/main.cc
@@ -579,6 +579,7 @@ static Dart_Handle EnvironmentCallback(Dart_Handle name) {
 static Dart_Isolate CreateIsolateAndSetupHelper(const char* script_uri,
                                                 const char* main,
                                                 const char* package_root,
+                                                Dart_IsolateFlags* flags,
                                                 char** error,
                                                 int* exit_code) {
   ASSERT(script_uri != NULL);
@@ -588,6 +589,7 @@ static Dart_Isolate CreateIsolateAndSetupHelper(const char* script_uri,
   isolate = Dart_CreateIsolate(script_uri,
                                main,
                                isolate_snapshot_buffer,
+                               flags,
                                isolate_data,
                                error);
 
@@ -673,7 +675,11 @@ static Dart_Isolate CreateIsolateAndSetupHelper(const char* script_uri,
 static Dart_Isolate CreateIsolateAndSetup(const char* script_uri,
                                           const char* main,
                                           const char* package_root,
+                                          Dart_IsolateFlags* flags,
                                           void* data, char** error) {
+  // The VM should never call the isolate helper with a NULL flags.
+  ASSERT(flags != NULL);
+  ASSERT(flags->version == DART_FLAGS_CURRENT_VERSION);
   IsolateData* parent_isolate_data = reinterpret_cast<IsolateData*>(data);
   int exit_code = 0;
   if (script_uri == NULL) {
@@ -697,6 +703,7 @@ static Dart_Isolate CreateIsolateAndSetup(const char* script_uri,
   return CreateIsolateAndSetupHelper(script_uri,
                                      main,
                                      package_root,
+                                     flags,
                                      error,
                                      &exit_code);
 }
@@ -967,6 +974,7 @@ void main(int argc, char** argv) {
   Dart_Isolate isolate = CreateIsolateAndSetupHelper(script_name,
                                                      "main",
                                                      commandline_package_root,
+                                                     NULL,
                                                      &error,
                                                      &exit_code);
   if (isolate == NULL) {