Reduce unnecessary usage of TextCaseSensitivity::TextCaseInsensitive.

third_party/WebKit/Source/core/html/parser/HTMLParserIdioms.cpp

 /*
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 331 matching lines @@
   if (!length || input.is8Bit())
     return parseHTMLListOfFloatingPointNumbersInternal(
         input.characters8(), input.characters8() + length);
   return parseHTMLListOfFloatingPointNumbersInternal(
       input.characters16(), input.characters16() + length);
 }
 
 static const char charsetString[] = "charset";
 static const size_t charsetLength = sizeof("charset") - 1;
 
+// https://html.spec.whatwg.org/multipage/infrastructure.html#extracting-character-encodings-from-meta-elements
 String extractCharset(const String& value) {
   size_t pos = 0;
   unsigned length = value.length();
 
   while (pos < length) {
-    pos = value.find(charsetString, pos, TextCaseInsensitive);
+    pos = value.find(charsetString, pos, TextCaseASCIIInsensitive);
     if (pos == kNotFound)
       break;
 
     pos += charsetLength;
 
     // Skip whitespace.
     while (pos < length && value[pos] <= ' ')
       ++pos;
 
     if (value[pos] != '=')
@@ skipping 122 matching lines @@
     string = StringImpl::create8BitIfPossible(characters, size);
   else if (width == Force8Bit)
     string = String::make8BitFrom16BitSource(characters, size);
   else
     string = String(characters, size);
 
   return string;
 }
 
 }  // namespace blink