Reduce the number of Uris parsed in builtin.

runtime/bin/dartutils.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 "bin/dartutils.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
@@ skipping 362 matching lines @@
   // Handle URI canonicalization requests.
   if (tag == Dart_kCanonicalizeUrl) {
     // If this is a Dart Scheme URL or 'part' of a io library
     // then it is not modified as it will be handled internally.
     if (is_dart_scheme_url || is_io_library) {
       return url;
     }
     // Resolve the url within the context of the library's URL.
     Dart_Handle builtin_lib =
         Builtin::LoadAndCheckLibrary(Builtin::kBuiltinLibrary);
-    Dart_Handle library_url = Dart_LibraryUrl(library);
-    if (Dart_IsError(library_url)) {
-      return library_url;
-    }
     return ResolveUri(library_url, url, builtin_lib);
   }
 
   // Handle 'import' of dart scheme URIs (i.e they start with 'dart:').
   if (is_dart_scheme_url) {
     if (tag == Dart_kImportTag) {
       // Handle imports of other built-in libraries present in the SDK.
       if (DartUtils::IsDartIOLibURL(url_string)) {
         return Builtin::LoadLibrary(url, Builtin::kIOLibrary);
       }
@@ skipping 578 matching lines @@
       new CObjectString(CObject::NewString(os_error->message()));
   CObjectArray* result = new CObjectArray(CObject::NewArray(3));
   result->SetAt(0, new CObjectInt32(CObject::NewInt32(kOSError)));
   result->SetAt(1, new CObjectInt32(CObject::NewInt32(os_error->code())));
   result->SetAt(2, error_message);
   return result;
 }
 
 }  // namespace bin
 }  // namespace dart