Sorry if the thread name isnt really clear, and i pointed the newest version but i noticed it on the r109 too.
The issue is that sometimes, the object using the platform behavior after landing, it will go a pixel inside the solids.
Heres some screenshots, one from my own project i started a few hours ago
<img src="http://imageshack.us/a/img853/803/13639169.png" border="0" />
And two from a game from the arcade which i forgot the name now (sorry <img src="smileys/smiley9.gif" border="0" align="middle" />)
<img src="http://imageshack.us/a/img69/2825/32895595.png" border="0" />
<img src="http://imageshack.us/a/img15/6360/39404251.png" border="0" />
On the first image you can see his little feet is perfectly aligned with the grass pixels, but on the second one it goes a pixel down into the grass.
Heres the capx
and an exported link
Tested on Rockmelt (which is pretty much Chrome) and Firefox, Windows 7, NVidia Geforce 9800 gt