Add settings for tuning WebKit tiled backing store

:Release Notes:
Added settings for the webkit TiledBackingStore tile size, and for
disabling power of two dimension enforcement in UpdateAtlas allocation.

:Detailed Notes:
- Added new settings tileWidth and TileHeight in General section, for
  changing the default tile sizes in TiledBackingStore.
- Added new setting nonPowerOfTwoUpdateAtlas, for disabling power of
  two enforcement on the area allocation of UpdateAtlas.

:Testing Performed:
Tried combined with webappmanager2 change and webkit2 change, and the
parameters take effect. For checking it I used the environment variable
WEBKIT_SHOW_COMPOSITING_DEBUG_VISUALS=1

:QA Notes:

:Issues Addressed:
[GF-8469] [Memory] Use an optimal backing store tile size on wam2

Open-webOS-DCO-1.0-Signed-off-by: Jose Dapena Paz <jose.dapena@lge.com>

Change-Id: I66de4f1c75100ed9c5236fc80a3cc644c9238854
Reviewed-on: https://g2g.palm.com/2835
Reviewed-by: Build Verification
Reviewed-by: Jose Dapena <jose.dapena@lge.com>
Tested-by: Jose Dapena <jose.dapena@lge.com>
Reviewed-by: Alexander Irhin <alexander.irhin@lge.com>
Reviewed-by: Eric Blade <eric.blade@lge.com>
Add "number of cached WebKit UpdateAtlases" setting

:Release Notes:
Add setting for the WebKit2 Coordinated Graphics System UpdateAtlases.

:Detailed Notes:
- Added new setting numberOfUpdateAtlases - number of cached UpdateAtlases
which is used to render the content on them.

:Testing Performed:
That parameter takes effect when was combined with commits to WebKit and WAM2.

:QA Notes:
This change is required for:
- https://g2g.palm.com/#/c/2883/ (webappmanager2)
and relates to:
- https://gpro.palm.com/#/c/6489/ (webkit-starfish)

:Issues Addressed:
[GF-9858] [WAM2] Cache Update Atlases to speed up animations
[GF-7084] [Enyo Perf] Keep 3-4 UpdateAtlases cached

Open-webOS-DCO-1.0-Signed-off-by: Andrey Volykhin <andrey.volykhin@lge.com>

Change-Id: Ic7bb5445dbd03d8b433487c186eac22defeaf009
Reviewed-on: https://g2g.palm.com/2881
Tested-by: Andrey Volykhin <andrey.volykhin@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Jose Dapena <jose.dapena@lge.com>
Reviewed-by: Andrey Volykhin <andrey.volykhin@lge.com>
Tested-by: Eric Blade <eric.blade@lge.com>
Reviewed-by: Eric Blade <eric.blade@lge.com>
Merge remote-tracking branch 'upstream/master' into webOS-ports/master
Add some animation related classes from luna-sysmgr

They are mostly related to the handling of animations of the luna-sysmgr UI but with our
ongoing efforts in having luna-sysmgr as a system service only we need to expose those
classes from here.

Signed-off-by: Simon Busch <morphis@gravedo.de>