Reland 166223 "Optimize SaveRegister stubs on arm and a64""

pop always requires a register list, even if it only contains one
registers

TBR=dglazkov@chromium.org
BUG=none

Review URL: https://codereview.chromium.org/151433003

git-svn-id: svn://svn.chromium.org/blink/trunk@166237 bbb929c8-8fbe-4397-9dbb-9b2b20218538