Replace WTF::emptyString{16Bit}() with a static global

third_party/WebKit/Source/core/frame/Deprecation.cpp

 // 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.
 
 #include "core/frame/Deprecation.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/frame/FrameConsole.h"
 #include "core/frame/FrameHost.h"
@@ skipping 112 matching lines @@
     case CSSPropertyAliasMotionPath:
       return replacedWillBeRemoved("motion-path", "offset-path", M58,
                                    "6390764217040896");
     case CSSPropertyMotion:
       return replacedWillBeRemoved("motion", "offset", M58, "6390764217040896");
     case CSSPropertyOffsetRotation:
       return replacedWillBeRemoved("offset-rotation", "offset-rotate", M58,
                                    "6390764217040896");
 
     default:
-      return emptyString();
+      return emptyString;
   }
 }
 
 void Deprecation::countDeprecation(const LocalFrame* frame,
                                    UseCounter::Feature feature) {
   if (!frame)
     return;
   FrameHost* host = frame->host();
   if (!host || host->deprecation().m_muteCount)
     return;
@@ skipping 281 matching lines @@
           "-internal-media-controls-text-track-list* selectors", M59,
           "5661431349379072");
 
     // Features that aren't deprecated don't have a deprecation message.
     default:
       return String();
   }
 }
 
 }  // namespace blink