Remove deprecated StringBuffer.add, addAll and addCharCode.

sdk/lib/html/html_common/lists.dart

Index: sdk/lib/html/html_common/lists.dart
diff --git a/sdk/lib/html/html_common/lists.dart b/sdk/lib/html/html_common/lists.dart
index 03cc29e5ccded15e85c4bd2d2a90906cdab186f5..2b5306a2b86ab9251c0078d3dfef838cd013a3d3 100644
--- a/sdk/lib/html/html_common/lists.dart
+++ b/sdk/lib/html/html_common/lists.dart
@@ -73,13 +73,13 @@ class Lists {
     StringBuffer buffer = new StringBuffer();
     if (separator == null || separator == "") {
       for (int i = 0; i < list.length; i++) {
-        buffer.add("${list[i]}");
+        buffer.write("${list[i]}");
       }
     } else {
-      buffer.add("${list[0]}");
+      buffer.write("${list[0]}");
       for (int i = 1; i < list.length; i++) {
-        buffer.add(separator);
-        buffer.add("${list[i]}");
+        buffer.write(separator);
+        buffer.write("${list[i]}");
       }
     }
     return buffer.toString();