Implement automatic loading of dart:core_native_fields library

vm/parser.cc

Index: vm/parser.cc
===================================================================
--- vm/parser.cc	(revision 1520)
+++ vm/parser.cc	(working copy)
@@ -3096,9 +3096,18 @@
 
 
 Dart_Handle Parser::CallLibraryTagHandler(Dart_LibraryTag tag,
-                                   intptr_t token_pos,
-                                   const String& url) {
+                                          intptr_t token_pos,
+                                          const String& url) {
   Dart_LibraryTagHandler handler = Isolate::Current()->library_tag_handler();
+  bool is_native_flds_library_url = url.Equals("dart:core-native-fields");
+  if (is_native_flds_library_url) {
+    if (tag == kCanonicalizeUrl) {
+      return Api::NewLocalHandle(url);
+    }
+    const Library& library = Library::Handle(Library::LookupLibrary(url));
+    ASSERT(!library.IsNull());
+    return Api::NewLocalHandle(library);
+  }
   if (handler == NULL) {
     ErrorMsg(token_pos, "no library handler registered");
   }