Fix a problem with const initialization in the top-level code generator.

Fix a problem with const initialization in the top-level code generator.

When initializing the special local variable containing the reference to the enclosing
function in named functions we now (correctly) emit an INIT_CONST instead of INIT_VAR,
and we correctly bail out in the top-level code generator.

Also part of this change is adding missing statement position information
for some statements in the top-level code generator.

Review URL: http://codereview.chromium.org/536029

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3587 ce2b1a6d-e550-0410-aec6-3dcde31c8c00