Bug 952977: Convert SnapTransforms to gfx::Matrix r=nical
Bug 952977: Convert ComputeEffectiveTransforms to gfx::Matrix4x4 r=nical
Bug 952977: Convert GetLocalTransform to gfx::Matrix4x4 r=nical
Bug 952977: Convert SetBaseTransform to gfx::Matrix4x4 r=nical
Bug 952977: Convert GetTransform to gfx::Matrix4x4 r=nical
Bug 952977: Convert Layer's mTransform to gfx::Matrix4x4 r=nical
Bug 952977: Convert shadow transforms to gfx::Matrix4x4 r=nical