Replace StringImpl::empty{16Bit}() with a static member

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

Index: third_party/WebKit/Source/wtf/text/WTFString.h
diff --git a/third_party/WebKit/Source/wtf/text/WTFString.h b/third_party/WebKit/Source/wtf/text/WTFString.h
index 6fe8763e5076193f44d79a270f1aa9c81d47fc66..048c62abf93989016b4e0679b0b0d5b7a199db0c 100644
--- a/third_party/WebKit/Source/wtf/text/WTFString.h
+++ b/third_party/WebKit/Source/wtf/text/WTFString.h
@@ -102,7 +102,7 @@ class WTF_EXPORT String {
   template <typename CharType>
   static String adopt(StringBuffer<CharType>& buffer) {
     if (!buffer.length())
-      return StringImpl::empty();
+      return StringImpl::empty;
     return String(buffer.release());
   }
 
@@ -494,7 +494,7 @@ inline void swap(String& a, String& b) {
 template <size_t inlineCapacity>
 String::String(const Vector<UChar, inlineCapacity>& vector)
     : m_impl(vector.size() ? StringImpl::create(vector.data(), vector.size())
-                           : StringImpl::empty()) {}
+                           : StringImpl::empty) {}
 
 template <>
 inline const LChar* String::getCharacters<LChar>() const {