Remove new space allocation in optimizing compiler, use Symbols::FromConcat where appropriate

runtime/vm/class_finalizer.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/class_finalizer.h"
 
 #include "vm/code_generator.h"
 #include "vm/flags.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
@@ skipping 1624 matching lines @@
       // level. As a consequence, if this mixin application is used itself as a
       // mixin in another mixin application, the bounds will be ignored, which
       // is correct, because the other mixin application does not inherit from
       // the super class of its mixin. Note also that the other mixin
       // application will only mixin the last mixin type listed in the first
       // mixin application it is mixing in.
       param_bound = isolate->object_store()->object_type();
       for (intptr_t i = 0; i < num_super_type_params; i++) {
         param ^= super_type_params.TypeAt(i);
         param_name = param.name();
-        param_name = String::Concat(param_name, Symbols::Backtick());
-        param_name = Symbols::New(param_name);
+        param_name = Symbols::FromConcat(param_name, Symbols::Backtick());
         cloned_param = TypeParameter::New(mixin_app_class,
                                           cloned_index,
                                           param_name,
                                           param_bound,
                                           param.token_pos());
         cloned_type_params.SetTypeAt(cloned_index, cloned_param);
         // Change the type arguments of the super type to refer to the
         // cloned type parameters of the mixin application class.
         super_type_args.SetTypeAt(cloned_index, cloned_param);
         cloned_index++;
@@ skipping 440 matching lines @@
   const intptr_t num_functions = functions.Length();
   Function& func = Function::Handle();
   for (intptr_t i = 0; i < num_functions; i++) {
     func ^= functions.At(i);
     if (func.IsGenerativeConstructor()) {
       // Build constructor name from mixin application class name
       // and name of cloned super class constructor.
       const String& ctor_name = String::Handle(func.name());
       String& clone_name = String::Handle(
           String::SubString(ctor_name, super_name.Length()));
-      clone_name = String::Concat(mixin_name, clone_name);
-      clone_name = Symbols::New(clone_name);
+      clone_name = Symbols::FromConcat(mixin_name, clone_name);
 
       if (FLAG_trace_class_finalization) {
         ISL_Print("Cloning constructor '%s' as '%s'\n",
                   ctor_name.ToCString(),
                   clone_name.ToCString());
       }
       const Function& clone = Function::Handle(
           Function::New(clone_name,
                         func.kind(),
                         func.is_static(),
@@ skipping 1101 matching lines @@
   ASSERT(fields_array.Length() == ByteBuffer::NumberOfFields());
   field ^= fields_array.At(0);
   ASSERT(field.Offset() == ByteBuffer::data_offset());
   name ^= field.name();
   expected_name ^= String::New("_data");
   ASSERT(String::EqualsIgnoringPrivateKey(name, expected_name));
 #endif
 }
 
 }  // namespace dart