Normalize and update the header value checks to RFC 7230 for Fetch

Source/modules/fetch/FetchHeaderList.h

Index: Source/modules/fetch/FetchHeaderList.h
diff --git a/Source/modules/fetch/FetchHeaderList.h b/Source/modules/fetch/FetchHeaderList.h
index 2aa9d0f8ddd1b10c4f1164a3cd7fcb6ef5e431e8..a31b7e1e59ccc352b9428bb6f12eaa2c9dcd660d 100644
--- a/Source/modules/fetch/FetchHeaderList.h
+++ b/Source/modules/fetch/FetchHeaderList.h
@@ -43,7 +43,7 @@ public:
     const Header& entry(size_t index) const { return *(m_headerList[index].get()); }
 
     static bool isValidHeaderName(const String&);
-    static bool isValidHeaderValue(const String&);
+    static bool isValidHeaderValueRFC7230(const String&);
 
     DEFINE_INLINE_TRACE() { }