adding HtmlEscape to dart:convert

pkg/intl/lib/bidi_formatter.dart

Index: pkg/intl/lib/bidi_formatter.dart
diff --git a/pkg/intl/lib/bidi_formatter.dart b/pkg/intl/lib/bidi_formatter.dart
index a9655f9497deeead6c9d5435f0e67db6e49a1d23..6ae39829e4154e7224ee76f6c7c79ff4b77a5045 100644
--- a/pkg/intl/lib/bidi_formatter.dart
+++ b/pkg/intl/lib/bidi_formatter.dart
@@ -86,18 +86,8 @@ class BidiFormatter {
    * included verbatim in HTML source code, either in an element body or in an
    * attribute value.
    */
-  String htmlEscape(String text) {
-    // TODO(alanknight): This is copied into here directly to avoid having a
-    // dependency on the htmlescape library, which is difficult to do in a way
-    // that's compatible with both package: links and direct links in the SDK.
-    // Once pub is used in test.dart (Issue #4968) this should be removed.
-    // TODO(efortuna): A more efficient implementation.
-    return text.replaceAll("&", "&")
-        .replaceAll("<", "&lt;")
-        .replaceAll(">", "&gt;")
-        .replaceAll('"', "&quot;")
-        .replaceAll("'", "&apos;");
-  }
+  @deprecated
+  String htmlEscape(String text) => HTML_ESCAPE.convert(text);
 
   /**
    * Formats a string of a given (or estimated, if not provided)
@@ -119,7 +109,7 @@ class BidiFormatter {
                       TextDirection direction}) {
     if (direction == null) direction = estimateDirection(text, isHtml: isHtml);
     var result;
-    if (!isHtml) text = htmlEscape(text);
+    if (!isHtml) text = HTML_ESCAPE.convert(text);
     var directionChange = contextDirection.isDirectionChange(direction);
     if (_alwaysSpan || directionChange) {
       var spanDirection = '';