Do not normalize into NFC the values of form fields

Source/core/platform/network/FormDataBuilder.cpp

Index: Source/core/platform/network/FormDataBuilder.cpp
diff --git a/Source/core/platform/network/FormDataBuilder.cpp b/Source/core/platform/network/FormDataBuilder.cpp
index 002865df0febea93834f7d5b775f3c1057f1aa26..3dbcd3af89cf225a268d6f67998a739e9c3916d5 100644
--- a/Source/core/platform/network/FormDataBuilder.cpp
+++ b/Source/core/platform/network/FormDataBuilder.cpp
@@ -162,7 +162,7 @@ void FormDataBuilder::addFilenameToMultiPartHeader(Vector<char>& buffer, const W
     // FIXME: This loses data irreversibly if the filename includes characters you can't encode
     // in the website's character set.
     append(buffer, "; filename=\"");
-    appendQuotedString(buffer, encoding.encode(filename, WTF::QuestionMarksForUnencodables));
+    appendQuotedString(buffer, encoding.normalizeAndEncode(filename, WTF::QuestionMarksForUnencodables));
     append(buffer, '"');
 }