ARM64: Slightly improve MacroAssembler::Allocate.

BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/247533005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20946 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
NameDictionary's key type is now Handle<Name> instead of Name*.

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/252383006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20947 ce2b1a6d-e550-0410-aec6-3dcde31c8c00