Implement fullPath method on File objects.

runtime/bin/file.cc

 // Copyright (c) 2011, 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/file.h"
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 
 #include "include/dart_api.h"
@@ skipping 234 matching lines @@
 
 
 void FUNCTION_NAME(File_Create)(Dart_NativeArguments args) {
   Dart_EnterScope();
   const char* str =
       DartUtils::GetStringValue(Dart_GetNativeArgument(args, 0));
   bool result = File::Create(str);
   Dart_SetReturnValue(args, Dart_NewBoolean(result));
   Dart_ExitScope();
 }
+
+
+void FUNCTION_NAME(File_FullPath)(Dart_NativeArguments args) {
+  Dart_EnterScope();
+  const char* str =
+      DartUtils::GetStringValue(Dart_GetNativeArgument(args, 0));
+  char* path = File::GetCanonicalPath(str);
+  if (path != NULL) {
+    Dart_SetReturnValue(args, Dart_NewString(path));
+    free(path);
+  }
+  Dart_ExitScope();
+}