Allow Dart_Null to be passed in for the import map in Dart_LoadLibrary and Dart_LoadScript.

vm/dart_api_impl.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 "include/dart_api.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart.h"
@@ skipping 2433 matching lines @@
   DARTSCOPE(isolate);
   const String& url_str = Api::UnwrapStringHandle(url);
   if (url_str.IsNull()) {
     RETURN_TYPE_ERROR(url, String);
   }
   const String& source_str = Api::UnwrapStringHandle(source);
   if (source_str.IsNull()) {
     RETURN_TYPE_ERROR(source, String);
   }
   const Array& mapping_array = Api::UnwrapArrayHandle(import_map);
-  if (mapping_array.IsNull()) {
-    RETURN_TYPE_ERROR(import_map, Array);
-  }
   Library& library = Library::Handle(isolate->object_store()->root_library());
   if (!library.IsNull()) {
     const String& library_url = String::Handle(library.url());
     return Api::NewError("%s: A script has already been loaded from '%s'.",
                          CURRENT_FUNC, library_url.ToCString());
   }
   isolate->set_library_tag_handler(handler);
   library = Library::New(url_str);
-  library.set_import_map(mapping_array);
+  if (mapping_array.IsNull()) {
+    library.set_import_map(Array::Handle(Array::Empty()));
+  } else {
+    library.set_import_map(mapping_array);
+  }
   library.Register();
   isolate->object_store()->set_root_library(library);
   Dart_Handle result;
   CompileSource(isolate,
                 library,
                 url_str,
                 source_str,
                 RawScript::kScript,
                 &result);
   return result;
@@ skipping 120 matching lines @@
   DARTSCOPE(isolate);
   const String& url_str = Api::UnwrapStringHandle(url);
   if (url_str.IsNull()) {
     RETURN_TYPE_ERROR(url, String);
   }
   const String& source_str = Api::UnwrapStringHandle(source);
   if (source_str.IsNull()) {
     RETURN_TYPE_ERROR(source, String);
   }
   const Array& mapping_array = Api::UnwrapArrayHandle(import_map);
-  if (mapping_array.IsNull()) {
-    RETURN_TYPE_ERROR(import_map, Array);
-  }
   Library& library = Library::Handle(Library::LookupLibrary(url_str));
   if (library.IsNull()) {
     library = Library::New(url_str);
-    library.set_import_map(mapping_array);
+    if (mapping_array.IsNull()) {
+      library.set_import_map(Array::Handle(Array::Empty()));
+    } else {
+      library.set_import_map(mapping_array);
+    }
     library.Register();
   } else if (!library.LoadNotStarted()) {
     // The source for this library has either been loaded or is in the
     // process of loading.  Return an error.
     return Api::NewError("%s: library '%s' has already been loaded.",
                          CURRENT_FUNC, url_str.ToCString());
   }
   Dart_Handle result;
   CompileSource(isolate,
                 library,
@@ skipping 82 matching lines @@
       *buffer = NULL;
     }
     delete debug_region;
   } else {
     *buffer = NULL;
     *buffer_size = 0;
   }
 }
 
 }  // namespace dart