Remove |AtomicString::DeprecatedLower()|

This patch removes now unused |AtomicString::DeprecatedLower()|.
The 6 calls to it were converted to |LowerASCII()| recently.

|String::DeprecatedLower()| still has 37 usages, and that the
underlying function is still needed.

Bug: 627682
Change-Id: I081be03de495712a2b252e30e95ff5f79c5d1e8f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1724153
Commit-Queue: Emil A Eklund <eae@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682884}

third_party/blink/renderer/platform/wtf/text/atomic_string.cc

@@ -71,17 +71,6 @@ AtomicString AtomicString::FromUTF8(const char* chars) {
   return AtomicString(AtomicStringTable::Instance().AddUTF8(chars, nullptr));
 }
 
-AtomicString AtomicString::DeprecatedLower() const {
-  // Note: This is a hot function in the Dromaeo benchmark.
-  StringImpl* impl = this->Impl();
-  if (UNLIKELY(!impl))
-    return *this;
-  scoped_refptr<StringImpl> new_impl = CaseMap::FastToLowerInvariant(impl);
-  if (LIKELY(new_impl == impl))
-    return *this;
-  return AtomicString(String(std::move(new_impl)));
-}
-
 AtomicString AtomicString::LowerASCII() const {
   StringImpl* impl = this->Impl();
   if (UNLIKELY(!impl))

third_party/blink/renderer/platform/wtf/text/atomic_string.h

@@ -174,15 +174,6 @@ class WTF_EXPORT AtomicString {
   }
   bool EndsWith(UChar character) const { return string_.EndsWith(character); }
 
-  // Returns a lowercase version of the string. This function might
-  // convert non-ASCII characters to ASCII characters. For example,
-  // DeprecatedLower() for U+212A is 'k'.
-  // This function is rarely used to implement web platform features.
-  // See crbug.com/627682.
-  // This function is deprecated. We should use LowerASCII(), or introduce
-  // LowerUnicode().
-  AtomicString DeprecatedLower() const;
-
   // Returns a lowercase/uppercase version of the string.
   // These functions convert ASCII characters only.
   AtomicString LowerASCII() const;