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

runtime/bin/main.cc

Index: runtime/bin/main.cc
diff --git a/runtime/bin/main.cc b/runtime/bin/main.cc
index be408da173628d16664f23c45b14a8ebb812e258..4812fa36e20a5b4c655ffdd783e9e785b7af0c19 100644
--- a/runtime/bin/main.cc
+++ b/runtime/bin/main.cc
@@ -243,7 +243,7 @@ static Dart_Handle LibraryTagHandler(Dart_LibraryTag tag,
   }
   result = DartUtils::LoadSource(NULL, library, url, tag, url_string);
   if (!Dart_IsError(result) && (tag == kImportTag)) {
-    Builtin::ImportLibrary(result);
+    Builtin::ImportLibrary(result, Builtin::kBuiltinLibrary);
   }
   return result;
 }
@@ -275,6 +275,15 @@ static bool CreateIsolateAndSetup(const char* name_prefix,
   if (script_snapshot_buffer != NULL) {
     library = Dart_LoadScriptFromSnapshot(script_snapshot_buffer);
   } else {
+    // If we are not using snapshots make sure that the builtin IO
+    // library is loaded so the main script can import it. Since we do
+    // not have a tag handler at this point, load the libraries needed
+    // by the IO library directly instead of relying on imports.
+    if (snapshot_buffer == NULL) {
+      Dart_Handle io_lib = Builtin::LoadLibrary(Builtin::kIOLibrary);
+      Builtin::ImportLibrary(io_lib, Builtin::kNativeWrappersLibrary);
+      Builtin::ImportLibrary(io_lib, Builtin::kCoreImplLibrary);
+    }
     library = LoadScript(canonical_script_name);
   }
   if (Dart_IsError(library)) {
@@ -294,11 +303,13 @@ static bool CreateIsolateAndSetup(const char* name_prefix,
     return false;
   }
   if (script_snapshot_buffer == NULL) {
-    Builtin::ImportLibrary(library);  // Implicitly import builtin into app.
+    // Implicitly import builtin into app.
+    Builtin::ImportLibrary(library, Builtin::kBuiltinLibrary);
   }
   if (snapshot_buffer != NULL) {
     // Setup the native resolver as the snapshot does not carry it.
-    Builtin::SetNativeResolver();
+    Builtin::SetNativeResolver(Builtin::kBuiltinLibrary);
+    Builtin::SetNativeResolver(Builtin::kIOLibrary);
   }
   Dart_ExitScope();
   return true;