Remove deprecated StringBuffer.add, addAll and addCharCode.

sdk/lib/_internal/compiler/samples/leap/leap_leg.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 compilerIsolate(port) {
   Runner runner = new Runner();
   runner.init();
 
   port.receive((msg, replyTo) {
     replyTo.send(runner.update(msg));
@@ skipping 124 matching lines @@
 
     Stopwatch sw = new Stopwatch()..start();
 
     LibraryElement e = compile(new LeapScript(codeText));
 
     void printFunction(FunctionElement fe, [String indentation = ""]) {
       var paramAcc = [];
 
       FunctionType ft = fe.computeType(compiler);
 
-      sb.add("<div>${indentation}");
+      sb.write("<div>${indentation}");
       ft.returnType.name.printOn(sb);
-      sb.add(" ");
+      sb.write(" ");
       fe.name.printOn(sb);
-      sb.add("(");
+      sb.write("(");
       ft.parameterTypes.printOn(sb, ", ");
-      sb.add(");</div>");
+      sb.write(");</div>");
 
     }
 
     void printField(FieldElement fe, [String indentation = ""]) {
-      sb.add("<div>${indentation}var ");
+      sb.write("<div>${indentation}var ");
       fe.name.printOn(sb);
-      sb.add(";</div>");
+      sb.write(";</div>");
     }
 
     void printClass(ClassElement ce) {
       ce.parseNode(compiler);
 
-      sb.add("<div>class ");
+      sb.write("<div>class ");
       ce.name.printOn(sb);
-      sb.add(" {");
+      sb.write(" {");
 
       for (Element e in ce.members.reverse()) {
         switch(e.kind) {
         case ElementKind.FUNCTION:
 
           printFunction(e, "&nbsp; ");
           break;
 
         case ElementKind.FIELD:
 
           printField(e, "&nbsp; ");
           break;
         }
       }
-      sb.add("}</div>");
+      sb.write("}</div>");
     }
 
     for (Element c in e.topLevelElements.reverse()) {
       switch (c.kind) {
       case ElementKind.FUNCTION:
         printFunction (c);
         break;
 
       case ElementKind.CLASS:
         printClass(c);
@@ skipping 86 matching lines @@
     mainApp = new LibraryElement(script);
 
     universe.libraries.remove(script.uri.toString());
     Element element;
     withCurrentElement(mainApp, () {
         scanner.scan(mainApp);
       });
     return mainApp;
   }
 }