Fix HTTP support in vm-service

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 1b9654bd1051eb25c6b65824d147e23aaa2e1ed3..4a5429131b580ff20af4b0e1b6407931d5ac1661 100644
--- a/runtime/bin/vmservice_impl.cc
+++ b/runtime/bin/vmservice_impl.cc
@@ -266,6 +266,9 @@ Dart_Handle VmService::GetSource(const char* name) {
   snprintf(&buffer[0], kBufferSize-1, "%s/%s", kLibrarySourceNamePrefix, name);
   const char* vmservice_source = NULL;
   int r = Resources::ResourceLookup(buffer, &vmservice_source);
+  if (r == Resources::kNoSuchInstance) {
+    FATAL1("vm-service: Could not find embedded source file: %s ", buffer);
+  }
   ASSERT(r != Resources::kNoSuchInstance);
   return Dart_NewStringFromCString(vmservice_source);
 }