Check that Dart_CreateIsolate is given a correct kind of snapshot.

runtime/vm/snapshot.cc

Index: runtime/vm/snapshot.cc
diff --git a/runtime/vm/snapshot.cc b/runtime/vm/snapshot.cc
index 08cf77ce3a9a7299cf79ad77175343a800e8f584..61506387d2ffa8a22982c4d24f18721cb91ccc57 100644
--- a/runtime/vm/snapshot.cc
+++ b/runtime/vm/snapshot.cc
@@ -132,6 +132,21 @@ static intptr_t GetTypeIndex(
 }
 
 
+const char* Snapshot::KindToCString(Kind kind) {
+  switch (kind) {
+    case kCore: return "core";
+    case kScript: return "script";
+    case kMessage: return "message";
+    case kAppWithJIT: return "app-jit";
+    case kAppNoJIT: return "app-aot";
+    case kNone: return "none";
+    case kInvalid:
+    default:
+      return "invalid";
+  }
+}
+
+
 // TODO(5411462): Temporary setup of snapshot for testing purposes,
 // the actual creation of a snapshot maybe done differently.
 const Snapshot* Snapshot::SetupFromBuffer(const void* raw_memory) {