[Qt][WK2] There's no way to test the gesture tap on WTR
https://bugs.webkit.org/show_bug.cgi?id=92895

Reviewed by Kenneth Rohde Christiansen.

Source/WebKit2:

Add an instance of QtViewportHandler to QQuickWebViewPrivate, so it's
now available on mobile and desktop modes, as a side effect gesture tap
events can now be created and sent to WebCore.

This is needed to test tap gestures and to get tap gestures working
when you have a WebView (in desktop mode) on notebooks equipped with
touch screens.

* UIProcess/API/qt/qquickwebview.cpp:
(QQuickWebViewPrivate::onComponentComplete):
(QQuickWebViewFlickablePrivate::onComponentComplete): Implementation
moved to QQuickWebViewPrivate::onComponentComplete.
* UIProcess/API/qt/qquickwebview_p_p.h:
(QQuickWebViewPrivate):
(QQuickWebViewFlickablePrivate):

Tools:

WTR doesn't create the QQuickItem from C++, not from QML, so a call
to componentComplete() was added to mimic the QML behaviour.

* WebKitTestRunner/qt/PlatformWebViewQt.cpp:
(WTR::PlatformWebView::PlatformWebView):


git-svn-id: svn://svn.chromium.org/blink/trunk@124625 bbb929c8-8fbe-4397-9dbb-9b2b20218538
bool QQuickWebViewExperimental::transparentBackground() const
{
    Q_D(const QQuickWebView);
    return d->transparentBackground();
}

bool QQuickWebViewExperimental::transparentBackground() const
{
    Q_D(const QQuickWebView);
    return d->transparentBackground();
}
