Unify ctx_iterator/ctx_begin()/ctx_end() and iterator/begin()/end() so that a single iterator type is used for both traversing decls of the same declaration context *and* of the parent declaration contexts, depending on the value of the bool parameter 'LookInParentCtx' that is passed to IdentifierResolver::begin().

llvm-svn: 53724

llvm-svn: 51151

-identifierResolver exposes an iterator interface to get all decls through the scope chain.
-The semantic staff (checking IdentifierNamespace and Doug's checking for shadowed tags were moved out of IdentifierResolver and back into Sema. IdentifierResolver just gives an iterator for all reachable decls of an identifier.

llvm-svn: 50923

llvm-svn: 49631

llvm-svn: 49628

llvm-svn: 49621

llvm-svn: 49582

Moved IdDeclInfo class to anonymous namespace.
Replaced array with a std::vector.

llvm-svn: 49570

llvm-svn: 49521