Unify most of our utf8 implementations. This takes the implementation

runtime/bin/dartutils.cc

Index: runtime/bin/dartutils.cc
===================================================================
--- runtime/bin/dartutils.cc	(revision 4630)
+++ runtime/bin/dartutils.cc	(working copy)
@@ -17,7 +17,7 @@
 const char* DartUtils::kIOLibURL = "dart:io";
 const char* DartUtils::kJsonLibURL = "dart:json";
 const char* DartUtils::kUriLibURL = "dart:uri";
-const char* DartUtils::kUtf8LibURL = "dart:utf8";
+const char* DartUtils::kUtfLibURL = "dart:utf";
 
 
 const char* DartUtils::kIdFieldName = "_id";
@@ -129,8 +129,8 @@
 }
 
 
-bool DartUtils::IsDartUtf8LibURL(const char* url_name) {
-  return (strcmp(url_name, kUtf8LibURL) == 0);
+bool DartUtils::IsDartUtfLibURL(const char* url_name) {
+  return (strcmp(url_name, kUtfLibURL) == 0);
 }