Translate viewport related meta tags into @viewport descriptors as suggested by the CSS Device Adap…

Source/core/page/FrameView.cpp

Index: Source/core/page/FrameView.cpp
diff --git a/Source/core/page/FrameView.cpp b/Source/core/page/FrameView.cpp
index db745bc881bc6d45e52d1ae5508869b1a7cc6932..a31e0b68e41e142a3dec5157929d7ffd95dc2336 100644
--- a/Source/core/page/FrameView.cpp
+++ b/Source/core/page/FrameView.cpp
@@ -2263,25 +2263,27 @@ void FrameView::performPostLayoutTasks()
 
     m_actionScheduler->resume();
 
-    // Viewport-dependent media queries may cause us to need completely different style information.
+    IntSize currentSize = layoutSize(IncludeScrollbars);
+    float currentZoomFactor = renderView->style()->zoom();
+    bool resized = !m_firstLayout && (currentSize != m_lastViewportSize || currentZoomFactor != m_lastZoomFactor);
+    m_lastViewportSize = currentSize;
+    m_lastZoomFactor = currentZoomFactor;
+
+    // Viewport-dependent media queries and @viewport rue may cause us to need completely
+    // different style information.
     if (m_frame->document()->styleResolver()->affectedByViewportChange()) {
+        if (resized)
+            m_frame->document()->styleResolver()->viewportStyleResolver()->resolve();
         m_frame->document()->styleResolverChanged(DeferRecalcStyle);
         InspectorInstrumentation::mediaQueryResultChanged(m_frame->document());
     }
 
     // Refetch render view since it can be destroyed by updateWidget() call above.
     renderView = this->renderView();
-    if (renderView && !renderView->printing()) {
-        IntSize currentSize = layoutSize(IncludeScrollbars);
-        float currentZoomFactor = renderView->style()->zoom();
-        bool resized = !m_firstLayout && (currentSize != m_lastViewportSize || currentZoomFactor != m_lastZoomFactor);
-        m_lastViewportSize = currentSize;
-        m_lastZoomFactor = currentZoomFactor;
-        if (resized) {
-            m_frame->eventHandler()->sendResizeEvent();
-            if (page && page->mainFrame() == m_frame)
-                InspectorInstrumentation::didResizeMainFrame(page);
-        }
+    if (renderView && !renderView->printing() && resized) {
+        m_frame->eventHandler()->sendResizeEvent();
+        if (page && page->mainFrame() == m_frame)
+            InspectorInstrumentation::didResizeMainFrame(page);
     }
 }