Beginning support for library prefixes in the dart API.

runtime/bin/builtin_nolib.cc

Index: runtime/bin/builtin_nolib.cc
diff --git a/runtime/bin/builtin_nolib.cc b/runtime/bin/builtin_nolib.cc
index eb95324c2ff23604a6a1d0f80d9ba680b1b86fb8..2b1654bd8479614ff3a1898155d20dae775d77f0 100644
--- a/runtime/bin/builtin_nolib.cc
+++ b/runtime/bin/builtin_nolib.cc
@@ -61,6 +61,9 @@ Dart_Handle Builtin::LoadLibrary(BuiltinLibraryId id) {
 
 void Builtin::ImportLibrary(Dart_Handle library, BuiltinLibraryId id) {
   Dart_Handle imported_library = LoadLibrary(id);
+  Dart_Handle prefix = Dart_NewString("");
   // Import the library into current library.
-  DART_CHECK_VALID(Dart_LibraryImportLibrary(library, imported_library));
+  DART_CHECK_VALID(Dart_LibraryImportLibrary(library,
+                                             imported_library,
+                                             prefix));
 }