incorrect walking speed in powdered snow on some blocks

Description:

When walking through powered snow, you are supposed to walk slower

however, when powdered snow is placed above a shorter block, only the lower block is affecting the speed, not the powdered snow.

Steps to reproduce:

• Place many soul sand blocks in a straight line
• Place powdered snow above all the soul sand blocks
• walk on the soul sand (through the powdered snow)
• Notice you are walking at soul sand speed and powered snow is not affecting the speed

dirt path also has this bug