This changes how FunctionTemplate interprets a Signature that specifies
compatible receivers and arguments. Only the hidden prototype chain will
be considered when searching for compatible receivers. This prevents
JavaScript from modifying the inheritance relationship set up by the
embedder.

R=rossberg@chromium.org
BUG=v8:2268
TEST=cctest/test-api

Review URL: https://codereview.chromium.org/11308197

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13131 ce2b1a6d-e550-0410-aec6-3dcde31c8c00