Optimize HitTestWithinLayer (20% faster HitTest).

Optimize HitTestWithinLayer (20% faster HitTest).

Whenever a temporary HitActor structure instance is created, constructor and destructor functions
are called for its .actor field.

In certain scenarios this results in creating and instantly deleting around 1000 dummy Actor
objects during a single call of HitTest().

HitTestWithinLayer is an important bottleneck in such scenarios, second only to
UpdateNodesAndAttachments (depending on the touchevent:framerate ratio).

This change makes the test around 20% faster and additionally reduces power consumption.

Change-Id: Iad9f59f39f6229516f036cc49025c2e0ef72ad3d