Fix the isolate unit tests to create an isolate from a snapshot.

runtime/vm/dart_api_impl_test.cc

Index: runtime/vm/dart_api_impl_test.cc
===================================================================
--- runtime/vm/dart_api_impl_test.cc	(revision 23633)
+++ runtime/vm/dart_api_impl_test.cc	(working copy)
@@ -2632,7 +2632,7 @@
   intptr_t mydata = 12345;
   char* err;
   Dart_Isolate isolate =
-      Dart_CreateIsolate(NULL, NULL, NULL,
+      Dart_CreateIsolate(NULL, NULL, bin::snapshot_buffer,
                          reinterpret_cast<void*>(mydata),
                          &err);
   EXPECT(isolate != NULL);
@@ -6685,7 +6685,9 @@
   {
     sync->Enter();
     char* error = NULL;
-    shared_isolate = Dart_CreateIsolate(NULL, NULL, NULL, NULL, &error);
+    shared_isolate = Dart_CreateIsolate(NULL, NULL,
+                                        bin::snapshot_buffer,
+                                        NULL, &error);
     EXPECT(shared_isolate != NULL);
     Dart_EnterScope();
     Dart_Handle url = NewString(TestCase::url());
@@ -6809,7 +6811,9 @@
 
   // Create an isolate.
   char* err;
-  Dart_Isolate isolate = Dart_CreateIsolate(NULL, NULL, NULL, my_data, &err);
+  Dart_Isolate isolate = Dart_CreateIsolate(NULL, NULL,
+                                            bin::snapshot_buffer,
+                                            my_data, &err);
   if (isolate == NULL) {
     OS::Print("Creation of isolate failed '%s'\n", err);
     free(err);