WTF: Add comments and tests for Unicode aware case-insensitive string operations.

third_party/WebKit/Source/wtf/text/StringView.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WTF_StringView_h
 #define WTF_StringView_h
 
 #include "wtf/Allocator.h"
 #include "wtf/GetPtr.h"
 #if DCHECK_IS_ON()
@@ skipping 197 matching lines @@
                             unsigned length) {
   SECURITY_DCHECK(offset + length <= impl.length());
   m_length = length;
   m_impl = const_cast<StringImpl*>(&impl);
   if (impl.is8Bit())
     m_characters8 = impl.characters8() + offset;
   else
     m_characters16 = impl.characters16() + offset;
 }
 
+// Unicode aware case insensitive string matching. Non-ASCII characters might
+// match to ASCII characters. These functions are rarely used to implement web
+// platform features.
 WTF_EXPORT bool equalIgnoringCase(const StringView&, const StringView&);
-WTF_EXPORT bool equalIgnoringASCIICase(const StringView&, const StringView&);
-
 WTF_EXPORT bool equalIgnoringCaseAndNullity(const StringView&,
                                             const StringView&);
 
+WTF_EXPORT bool equalIgnoringASCIICase(const StringView&, const StringView&);
+
 // TODO(esprehn): Can't make this an overload of WTF::equal since that makes
 // calls to equal() that pass literal strings ambiguous. Figure out if we can
 // replace all the callers with equalStringView and then rename it to equal().
 WTF_EXPORT bool equalStringView(const StringView&, const StringView&);
 
 inline bool operator==(const StringView& a, const StringView& b) {
   return equalStringView(a, b);
 }
 
 inline bool operator!=(const StringView& a, const StringView& b) {
   return !(a == b);
 }
 
 }  // namespace WTF
 
 using WTF::StringView;
 using WTF::equalIgnoringASCIICase;
 using WTF::equalIgnoringCase;
 
 #endif