Split dart:builtin into dart:builtin and dart:io.

runtime/vm/parser.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/compiler_stats.h"
@@ skipping 3302 matching lines @@
     }
     ExpectToken(Token::kRPAREN);
     ExpectToken(Token::kSEMICOLON);
     Dart_Handle handle = CallLibraryTagHandler(kCanonicalizeUrl,
                                                import_pos,
                                                url);
     const String& canon_url = String::CheckedHandle(Api::UnwrapHandle(handle));
     // Lookup the library URL.
     Library& library = Library::Handle(Library::LookupLibrary(canon_url));
     if (library.IsNull()) {
-      // Create a new library object and call the library tag handler.
-      library = Library::New(canon_url);
-      library.Register();
-      // The tag handler expects the importing library as a parameter.
+      // Call the library tag handler to load the library.
       CallLibraryTagHandler(kImportTag, import_pos, canon_url);
+      // If the library tag handler succeded without registering the
+      // library we create an empty library to import.
+      library = Library::LookupLibrary(canon_url);
+      if (library.IsNull()) {
+        library = Library::New(canon_url);
+        library.Register();
+      }
     }
     // Add the import to the library.
     if (prefix.IsNull() || (prefix.Length() == 0)) {
       library_.AddImport(library);
     } else {
       if (library_.LookupLocalObject(prefix) != Object::null()) {
         ErrorMsg(token_index_, "'%s' is already defined", prefix.ToCString());
       }
       const LibraryPrefix& library_prefix =
           LibraryPrefix::Handle(LibraryPrefix::New(prefix, library));
@@ skipping 4432 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart