VM: Service isolate under precompilation.

runtime/include/dart_api.h

Index: runtime/include/dart_api.h
diff --git a/runtime/include/dart_api.h b/runtime/include/dart_api.h
index b77cc427ef42d27d2ded2002179d754527954701..e79a5755038df1a0dfed9296ff28577c00cc312a 100755
--- a/runtime/include/dart_api.h
+++ b/runtime/include/dart_api.h
@@ -2715,6 +2715,15 @@ DART_EXPORT Dart_Handle Dart_LoadScriptFromSnapshot(const uint8_t* buffer,
  */
 DART_EXPORT Dart_Handle Dart_RootLibrary();
 
+
+/**
+ * Sets the root library for the current isolate.
+ *
+ * \return Returns an error handle if `library` is not a library handle.
+ */
+DART_EXPORT Dart_Handle Dart_SetRootLibrary(Dart_Handle library);
+
+
 /**
  * Lookup or instantiate a type by name and type arguments from a Library.
  *