json: Add defaultValue to QJsonValueRef toInt/toBool/toDouble/toString

Currently QJsonValue and QJsonValueRef behave differently in
regard to the default values leading to confusion compile errors
depending on which of the two types one is actually using. Before
this change it was possible to write:

QJsonValue value = jsonObject["item"];
QString name = value.toString(QStringLiteral("default"));

but not:

QString name = jsonObject["item"].toString(QStringLiteral("default"));

Change-Id: Id1185acf339aa3a91e97848e85d068f84552df71
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
Remove unused UserEventRegistrationBitFieldSize

It causes a clang warning (unused variable).

Change-Id: If3d0ec0a0b493a9b1d36e7a07db6cbe29bf789cb
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
Add support for querying "eglconfig" from eglfs

This makes it possible to retrieve the EGLConfig used by Qt to
create the QOpenGLContext. QtWebEngine needs this to be able to
get rid of EGL_BAD_MATCH errors on certain hardware by using the
exact same EGLConfig in Chromium as used by Qt.

Change-Id: I049c0d8637c44acfe160230e4bb81364d66413ab
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
Windows: Expose helper functions for QWindowsMime to the native interface.

Enable QWindowsMimeConverter to use external mime handlers which it
does not own.

Task-number: QTBUG-39559
Change-Id: Ife6607dffd9571fa4aa12fffdc61b42662182b0a
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>