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

Source/modules/fetch/FetchHeaderList.cpp

Index: Source/modules/fetch/FetchHeaderList.cpp
diff --git a/Source/modules/fetch/FetchHeaderList.cpp b/Source/modules/fetch/FetchHeaderList.cpp
index a03e9f3e3d39d1b679f12d5ba463588338253050..c1a2f1c19cbaed24e36a19bad5b3d6db313cef6e 100644
--- a/Source/modules/fetch/FetchHeaderList.cpp
+++ b/Source/modules/fetch/FetchHeaderList.cpp
@@ -149,11 +149,13 @@ bool FetchHeaderList::isValidHeaderName(const String& name)
     return isValidHTTPToken(name);
 }
 
-bool FetchHeaderList::isValidHeaderValue(const String& value)
+bool FetchHeaderList::isValidHeaderValueRFC7230(const String& value)
 {
-    // "A value is a byte sequence that matches the field-value token production
-    // and contains no 0x0A or 0x0D bytes."
-    return isValidHTTPHeaderValue(value);
+    // checks the header value according to the latest Fetch API's header
+    // value definition (https://fetch.spec.whatwg.org/#concept-header-value) and RFC
+    // 7230 and it is different from isValidHTTPHeaderValue().
+
+    return value.isEmpty() || isValidHTTPFieldContentRFC7230(value);
 }
 
 } // namespace blink