Make v8::TryCatch able to consume natively thrown exceptions (again).

R=yangguo@chromium.org
BUG=chromium:362388
TEST=cctest/test-api/TryCatchNative
LOG=N

Review URL: https://codereview.chromium.org/291393002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21456 ce2b1a6d-e550-0410-aec6-3dcde31c8c00