Reland: [turbofan] Various fixes to allow unboxed doubles as arguments in registers and on the stack.

OCL: https://codereview.chromium.org/1263033004/

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1284893002

Cr-Commit-Position: refs/heads/master@{#30115}