Add <meta viewport> support to the preloader

Source/core/css/MediaValuesCached.h

Index: Source/core/css/MediaValuesCached.h
diff --git a/Source/core/css/MediaValuesCached.h b/Source/core/css/MediaValuesCached.h
index c8d37f621f52fee9111f37a7fce02ba78943988b..4d4ba8003921e3cfed4a0fe936820d837d0bdedf 100644
--- a/Source/core/css/MediaValuesCached.h
+++ b/Source/core/css/MediaValuesCached.h
@@ -78,6 +78,10 @@ public:
     virtual const String mediaType() const override;
     virtual WebDisplayMode displayMode() const override;
 
+    void setViewportWidth(int);
+    void setViewportHeight(int);
+
+    virtual bool isCached() const override { return true; }
 protected:
     MediaValuesCached();
     MediaValuesCached(LocalFrame*);