Heap profiler currently gets "document" of global objects while taking snapshot (to later retrieve its "URL"). This is unsafe as there may be no current v8 context when the property is requested while corresponding property accessor may make some assumptions about the context stack during its invokation. Several crashes were reported due to this problem:
https://bugs.webkit.org/show_bug.cgi?id=103076
https://crbug.com/162121
https://crbug.com/132727

This patch adds a callback for resolving global object names and avoid the crashes.
Review URL: https://codereview.chromium.org/11415203

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13137 ce2b1a6d-e550-0410-aec6-3dcde31c8c00