Disable test discovery from the build system

CONFIG += testcase enables make check and the CI test planner
to find and execute tests. Since our tests aren't 100% passing
yet, disable them for now.

Change-Id: I0dbafa7f6d6176979b28249b0642905611d791c2
Reviewed-by: Arvid Nilsson <anilsson@blackberry.com>
Reviewed-by: Michael Bruning <michael.bruning@digia.com>
Quick: Support reparenting

To support reparenting, we make the compositing surface independent of
the window by using gfx::TEXTURE_TRANSPORT. We also need to be able to
keep frame data across window changes so we can reconstruct the QSGNode
tree in a new context, so extract that data into DelegatedFrameNodeData
class. Any context-specific data is still stored in DelegatedFrameNode.

Also hook up window changes to WebContents::WasShown/Hidden for Quick.
Remove checking of Qt isVisible state, this mechanism is used to sync
Chromium with Qt, not the other way around. WasShown/Hidden is
orthogonal to Show/Hide, and can use different triggers. However for
Widgets it probably makes sense to hook both up to widget visibility.

Change-Id: I1ef4b50cd61b8e54b791e03f0b41929c42fec8bf
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>