Don't scale WindowHeap in overview mode

when in overview mode, don't scale down WindowHeap, as this
will cause ugly glitches, but resize it down instead.
Still use transforms when it goes in desktop grid mode, at least for now

probably future further refactor can still help things

Before:

![image](/uploads/7ca83e7e9292bd8489faaf76d4c12693/image.png)

After:

![image](/uploads/27b970d056c89486661d6695d09813ff/image.png)

CCBUG:475682