Port r8496 (b7d5ecf0).

Original commit message:
Introduce scopes to keep track of catch blocks at compile time.
The catch variable is bound in the catch scope. For simplicity in this
initial implementation, it is always allocated even if unused and always
allocated to a catch context even if it doesn't escape. The presence of
catch is no longer treated as a with.
In this change, care must be taken to distinguish between the scope where a
var declaration is hoisted to and the scope where the initialization occurs.

BUG=
TEST=

Review URL: http://codereview.chromium.org//7212020
Patch from Paul Lind <plind44@gmail.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8522 ce2b1a6d-e550-0410-aec6-3dcde31c8c00