* Centralized AND/OR handling, keeping related code together.

* Removed HandleExpression/HandleInNonTestContext and introduced VisitInSameContext instead, making it more obvious what's actually going on.

* Consistently use a new context when visiting the left sub-expression of an AND/OR. Note that the context stacks in the full code generator and crankshaft are still a bit out of sync for the right sub-expression.
Review URL: http://codereview.chromium.org/6976028

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8124 ce2b1a6d-e550-0410-aec6-3dcde31c8c00