Use the new loader mechanism to resolve URIs and load script files in gen_snapshot. This should all…

runtime/bin/vmservice_impl.cc

Index: runtime/bin/vmservice_impl.cc
diff --git a/runtime/bin/vmservice_impl.cc b/runtime/bin/vmservice_impl.cc
index 273640860a22a2086c2e8a1be0a44071aac5b98c..b7f4df47680dc4098df1def39ed98df8d8899cfc 100644
--- a/runtime/bin/vmservice_impl.cc
+++ b/runtime/bin/vmservice_impl.cc
@@ -342,8 +342,8 @@ Dart_Handle VmService::LibraryTagHandler(Dart_LibraryTag tag,
     return result;
   }
   if (tag == Dart_kImportTag) {
-    // Embedder handles all requests for external libraries.
-    return DartUtils::LibraryTagHandler(tag, library, url);
+    UNREACHABLE();
+    return Dart_Null();
   }
   ASSERT((tag == Dart_kSourceTag) || (tag == Dart_kCanonicalizeUrl));
   if (tag == Dart_kCanonicalizeUrl) {