Use angleDelta instead of deprecated Qt4 delta

Switch to using the Qt5 angleDelta instead of the Qt4 style delta that
can only handle single orientation wheel events.

Change-Id: I181dda03c7fc9c676100cb31ab7717f9641b625e
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

src/core/web_event_factory.cpp

@@ -656,14 +656,11 @@ blink::WebMouseWheelEvent WebEventFactory::toWebWheelEvent(QWheelEvent *ev, doub
     webEvent.modifiers = modifiersForEvent(ev);
     webEvent.timeStampSeconds = currentTimeForEvent(ev);
 
-    if (ev->orientation() == Qt::Horizontal)
-        webEvent.wheelTicksX = ev->delta() / 120.0f;
-    else
-        webEvent.wheelTicksY = ev->delta() / 120.0f;
+    webEvent.wheelTicksX = ev->angleDelta().x() / QWheelEvent::DefaultDeltasPerStep;
+    webEvent.wheelTicksY = ev->angleDelta().y() / QWheelEvent::DefaultDeltasPerStep;
 
-
-    // Since we report the scroll by the pixel, convert the delta to pixel distance using standard scroll step.
-    // Use the same single scroll step as QTextEdit (in QTextEditPrivate::init [h,v]bar->setSingleStep)
+    // We can't use the device specific QWheelEvent::pixelDelta(), so we calculate
+    // a pixel delta based on ticks and scroll per line.
     static const float cDefaultQtScrollStep = 20.f;
 
     webEvent.deltaX = webEvent.wheelTicksX * wheelScrollLines * cDefaultQtScrollStep;