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/720676Reviewed-by: Joran Siu <joransiu@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#48593}