Minor restructure some of the builtin library processing code

bin/main.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 <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
 #include "include/dart_api.h"
 #include "include/dart_debugger_api.h"
@@ skipping 349 matching lines @@
     const int kNumArgs = 2;
     Dart_Handle dart_args[kNumArgs];
     dart_args[0] = library_url;
     dart_args[1] = url;
     return Dart_Invoke(
         builtin_lib, Dart_NewString("_resolveUri"), kNumArgs, dart_args);
   }
   if (is_dart_scheme_url) {
     ASSERT(tag == kImportTag);
     // Handle imports of other built-in libraries present in the SDK.
+    Builtin::BuiltinLibraryId id;
     if (DartUtils::IsDartCryptoLibURL(url_string)) {
-      return Builtin::LoadLibrary(Builtin::kCryptoLibrary);
+      id = Builtin::kCryptoLibrary;
     } else if (DartUtils::IsDartIOLibURL(url_string)) {
-      return Builtin::LoadLibrary(Builtin::kIOLibrary);
+      id = Builtin::kIOLibrary;
     } else if (DartUtils::IsDartJsonLibURL(url_string)) {
-      return Builtin::LoadLibrary(Builtin::kJsonLibrary);
+      id = Builtin::kJsonLibrary;
     } else if (DartUtils::IsDartUriLibURL(url_string)) {
-      return Builtin::LoadLibrary(Builtin::kUriLibrary);
+      id = Builtin::kUriLibrary;
     } else if (DartUtils::IsDartUtfLibURL(url_string)) {
-      return Builtin::LoadLibrary(Builtin::kUtfLibrary);
+      id = Builtin::kUtfLibrary;
     } else {
       return Dart_Error("Do not know how to load '%s'", url_string);
     }
+    return Builtin::LoadLibrary(id);
   } else {
     // Get the file path out of the url.
     Dart_Handle builtin_lib = Builtin::LoadLibrary(Builtin::kBuiltinLibrary);
     Dart_Handle file_path = FilePathFromUri(url, builtin_lib);
     if (Dart_IsError(file_path)) {
       return file_path;
     }
     Dart_StringToCString(file_path, &url_string);
   }
   if (is_dart_extension_url) {
@@ skipping 365 matching lines @@
   DumpPprofSymbolInfo();
   // Shutdown the isolate.
   Dart_ShutdownIsolate();
   // Terminate process exit-code handler.
   Process::TerminateExitCodeHandler();
 
   free(const_cast<char*>(original_working_directory));
 
   return 0;
 }