Background compilation fixes

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index defdcc5332423e8ce2cd3dffef24e0a46f6d8011..73e6eae6171eee8a973a98b372bbb9613285a786 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -13556,14 +13556,15 @@ const char* Code::ToCString() const {
 }
 
 
+// Called by disassembler.
 RawString* Code::Name() const {
   const Object& obj = Object::Handle(owner());
   if (obj.IsNull()) {
     // Regular stub.
     const char* name = StubCode::NameOfStub(EntryPoint());
     ASSERT(name != NULL);
-    const String& stub_name = String::Handle(String::New(name));
-    return String::Concat(Symbols::StubPrefix(), stub_name);
+    const String& stub_name = String::Handle(Symbols::New(name));
+    return Symbols::FromConcat(Symbols::StubPrefix(), stub_name);
   } else if (obj.IsClass()) {
     // Allocation stub.
     const Class& cls = Class::Cast(obj);