This patch changes the signature of the v8::HeapGraphNode::GetRetainedSize method, but it's not used in Chromium, and it should be easy for other clients (if any) to adjust to this change.

BUG=none
TEST=none

Review URL: https://chromiumcodereview.appspot.com/9466014
Patch from Alexei Filippov <alexeif@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10846 ce2b1a6d-e550-0410-aec6-3dcde31c8c00