followup to fixed bug 77992
[qtmozembed] WIP: Drop private API usage

TODO:
- All NO_PRIVATE_API blocks should be dropped
- init() and initialize() should be combined (didn't do yet, so that diff is clearer)
- Rename onInitialized to something like onContextInitialized
Merge pull request #78 from rainemak/dropPrivateAPIUsage

[qtmozembed] WIP: Drop private API usage
[qtmozembed] Cleanup startup sequence

- If mozcontext ready, view created on component completed.
- Creation of render object connected to beforeSynchronizing, no
  need anymore for scenegraph initialized connection. The beforeSynchronizing
  is also good in sense that the GUI thread is locked.
- Due to above GL context used for rendering is bound and QSGThreadObject
  could be made self-contained.
Cleanup NO_PRIVATE_API ifndef blocks and related sources
Merge pull request #79 from rainemak/removeNoPrivateApi

Clean NO_PRIVATE_API usage
[qtmozembed] Sync with upstream. Merge remote-tracking branch 'origin/master'