Make (some) functions called from builtin functions use the callback's global as receiver.

Make (some) functions called from builtin functions use the callback's global as receiver.

Changes GetGlobalReceiver() to GetDefaultReceiver(func) that returns undefined
for strict and native functions, and the function's context's global proxy
for "normal" functions.

BUG=v8:1547
TEST=cctest/api-test/ForeignFunctionReceiver

Committed: http://code.google.com/p/v8/source/detail?r=9030

[Vyacheslav Egorov (Chromium), 2011-08-26 13:32:42]

LGTM