Only need to re-evaluate MQ on resize.

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 798 matching lines @@
     // Don't schedule more layouts, we're in one.
     TemporaryChange<bool> changeSchedulingEnabled(m_layoutSchedulingEnabled, false);
 
     if (!m_nestedLayoutCount && !m_inSynchronousPostLayout && m_postLayoutTasksTimer.isActive()) {
         // This is a new top-level layout. If there are any remaining tasks from the previous layout, finish them now.
         m_inSynchronousPostLayout = true;
         performPostLayoutTasks();
         m_inSynchronousPostLayout = false;
     }
 
+    bool wasResized = wasViewportResized();
     Document* document = m_frame->document();
-    if (wasViewportResized())
+    if (wasResized)
         document->notifyResizeForViewportUnits();
 
     // Viewport-dependent media queries may cause us to need completely different style information.
-    if (!document->styleResolver() || document->styleResolver()->mediaQueryAffectedByViewportChange()) {
+    if (!document->styleResolver() || (wasResized && document->styleResolver()->mediaQueryAffectedByViewportChange())) {
         document->styleResolverChanged();
         document->mediaQueryAffectingValueChanged();
-    } else {
+    } else if (wasResized) {
         document->evaluateMediaQueryList();
     }
 
     document->updateRenderTreeIfNeeded();
     lifecycle().advanceTo(DocumentLifecycle::StyleClean);
 }
 
 void FrameView::performLayout(RenderObject* rootForThisLayout, bool inSubtreeLayout)
 {
     TRACE_EVENT0("blink,benchmark", "FrameView::performLayout");
@@ skipping 3200 matching lines @@
 {
     Settings* settings = frame().settings();
     if (!settings || !settings->rootLayerScrolls())
         return this;
 
     RenderView* renderView = this->renderView();
     return renderView ? renderView->scrollableArea() : nullptr;
 }
 
 } // namespace blink