Add support for `width` based Width Client Hint

Source/core/html/HTMLImageElement.h

Index: Source/core/html/HTMLImageElement.h
diff --git a/Source/core/html/HTMLImageElement.h b/Source/core/html/HTMLImageElement.h
index 69e2b5c74308fe256519525207c7b88924ef912e..c5f7e61874e880a50b5d3e12652f9e27d71f739a 100644
--- a/Source/core/html/HTMLImageElement.h
+++ b/Source/core/html/HTMLImageElement.h
@@ -25,6 +25,7 @@
 #define HTMLImageElement_h
 
 #include "core/CoreExport.h"
+#include "core/fetch/FetchRequest.h"
 #include "core/html/HTMLElement.h"
 #include "core/html/HTMLImageLoader.h"
 #include "core/html/canvas/CanvasImageSource.h"
@@ -108,6 +109,8 @@ public:
     void setUseFallbackContent();
     void setIsFallbackImage() { m_isFallbackImage = true; }
 
+    static int widthAttributeToInt(const String& value, bool& isValid);
+    FetchRequest::ResourceWidth resourceWidth();
     float sourceSize(Element&);
 
     void forceReload() const;