Add WTF::String::emptyString16Bit

Source/wtf/text/StringStatics.cpp

Index: Source/wtf/text/StringStatics.cpp
diff --git a/Source/wtf/text/StringStatics.cpp b/Source/wtf/text/StringStatics.cpp
index 099f00115619cdf3403f25e96563bff563f4b6f2..9231216e192fe35d67e40d007828b0a9be01a19a 100644
--- a/Source/wtf/text/StringStatics.cpp
+++ b/Source/wtf/text/StringStatics.cpp
@@ -37,7 +37,16 @@ namespace WTF {
 StringImpl* StringImpl::empty()
 {
     DEFINE_STATIC_LOCAL(StringImpl, emptyString, (ConstructEmptyString));
-    WTF_ANNOTATE_BENIGN_RACE(&emptyString, "Benign race on StringImpl::emptyString reference counter");
+    WTF_ANNOTATE_BENIGN_RACE(&emptyString,
+        "Benign race on the reference counter of a static string created by StringImpl::empty");
+    return &emptyString;
+}
+
+StringImpl* StringImpl::empty16Bit()
+{
+    DEFINE_STATIC_LOCAL(StringImpl, emptyString, (ConstructEmptyString16Bit));
+    WTF_ANNOTATE_BENIGN_RACE(&emptyString,
+        "Benign race on the reference counter of a static string created by StringImpl::empty16Bit");
     return &emptyString;
 }