Add ascii() / latin1() / utf8() methods to AtomicString to avoid having to call string()

Source/platform/text/TextBreakIteratorInternalICU.cpp

Index: Source/platform/text/TextBreakIteratorInternalICU.cpp
diff --git a/Source/platform/text/TextBreakIteratorInternalICU.cpp b/Source/platform/text/TextBreakIteratorInternalICU.cpp
index 131a04175d8457c9dee0ffef39f4050b68952a3f..e28a5276e6cb7dbe0c0045b25833d41cc4e67249 100644
--- a/Source/platform/text/TextBreakIteratorInternalICU.cpp
+++ b/Source/platform/text/TextBreakIteratorInternalICU.cpp
@@ -33,7 +33,7 @@ static const char* UILanguage()
 {
     // Chrome's UI language can be different from the OS UI language on Windows.
     // We want to return Chrome's UI language here.
-    DEFINE_STATIC_LOCAL(CString, locale, (defaultLanguage().string().latin1()));
+    DEFINE_STATIC_LOCAL(const CString, locale, (defaultLanguage().latin1()));
     return locale.data();
 }