Remove deprecated StringBuffer.add, addAll and addCharCode.

sdk/lib/_internal/compiler/implementation/ssa/codegen.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/codegen.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/codegen.dart b/sdk/lib/_internal/compiler/implementation/ssa/codegen.dart
index 62456a1ad9b7873c379cb3a5b2a6a303777ec7d3..a03098b5e959ebea2cf5ff872c94cf39100d5211 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/codegen.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/codegen.dart
@@ -79,10 +79,8 @@ class SsaCodeGeneratorTask extends CompilerTask {
         // arguments, the emitter will generate stubs to handle them,
         // and needs to know if the method is overridden.
         nativeEmitter.overriddenMethods.add(element);
-        StringBuffer buffer = new StringBuffer();
-        body =
-            nativeEmitter.generateMethodBodyWithPrototypeCheckForElement(
-                element, codegen.body, codegen.parameters);
+        body = nativeEmitter.generateMethodBodyWithPrototypeCheckForElement(
+                  element, codegen.body, codegen.parameters);
       } else {
         body = codegen.body;
       }