Windows compile fix

Change-Id: I2321ae9310476f36a1b1fa36509ec92f639ee8a7
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>
QmlDesigner: Exchange QWeakPointer with QPointer

Because we compile only with Qt 5.

Change-Id: I2c6496f37550438f7c8ccbf8af0090c525b87d8f
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>