This is a reland of af49af00
Original change's description:
> PPC/s390: Fix arguement handling
> 
> 1. in AssembleMove and AssembleSwap, we need to distinguish Double and Float
> 2. in 32-bit mode, double needs to be counted as 2 slots in stack
> 
> R=joransiu@ca.ibm.com, jbarboza@ca.ibm.com, michael_dawson@ca.ibm.com, mmallick@ca.ibm.com
> 
> Bug: 
> Change-Id: Iffe1844aa72e9d4c9492034c3df9a994e1304a27
> Reviewed-on: https://chromium-review.googlesource.com/720676
> Reviewed-by: Joran Siu <joransiu@ca.ibm.com>
> Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
> Cr-Commit-Position: refs/heads/master@{#48593}

Change-Id: If91125e71b82c92f54f537345e4c213bd185e786
Reviewed-on: https://chromium-review.googlesource.com/721419Reviewed-by: Joran Siu <joransiu@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#48610}