Use zone when allocating handles in FlowGraphCompiler assembling operations. Add profiling VM tags…

runtime/vm/tags.cc

 // Copyright (c) 2014, 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/tags.h"
 
 #include "vm/isolate.h"
 #include "vm/json_stream.h"
 #include "vm/native_entry.h"
 #include "vm/runtime_entry.h"
@@ skipping 63 matching lines @@
 VMTag::TagEntry VMTag::entries_[] = {
   { "InvalidTag", kInvalidTagId, },
 #define DEFINE_VM_TAG_ENTRY(tag)                                               \
   { ""#tag, k##tag##TagId },
   VM_TAG_LIST(DEFINE_VM_TAG_ENTRY)
 #undef DEFINE_VM_TAG_ENTRY
   { "kNumVMTags", kNumVMTags },
 };
 
 
-VMTagScope::VMTagScope(Isolate* base_isolate, uword tag)
+VMTagScope::VMTagScope(Isolate* base_isolate, uword tag, bool conditional_set)
     : StackResource(base_isolate) {
   ASSERT(isolate() != NULL);
   previous_tag_ = isolate()->vm_tag();
-  isolate()->set_vm_tag(tag);
+  if (conditional_set) {
+    isolate()->set_vm_tag(tag);
+  }
 }
 
 
 VMTagScope::~VMTagScope() {
   ASSERT(isolate() != NULL);
   isolate()->set_vm_tag(previous_tag_);
 }
 
 
 VMTagCounters::VMTagCounters() {
@@ skipping 47 matching lines @@
   Isolate* isolate = Isolate::Current();
   const UserTag& tag =
       UserTag::Handle(isolate, UserTag::FindTagById(tag_id));
   ASSERT(!tag.IsNull());
   const String& label = String::Handle(isolate, tag.label());
   return label.ToCString();
 }
 
 
 }  // namespace dart