Factor cpu profile tree into separate element and expose allocation tracing UI

runtime/vm/tags.cc

Index: runtime/vm/tags.cc
diff --git a/runtime/vm/tags.cc b/runtime/vm/tags.cc
index 0b8e75e98c879b04dc3e5a0a5ba5dd5cccd78443..50e5e237d34a6e2ed5f404aae65ef71e24f6b72b 100644
--- a/runtime/vm/tags.cc
+++ b/runtime/vm/tags.cc
@@ -33,17 +33,13 @@ const char* VMTag::TagName(uword tag) {
 
 
 bool VMTag::IsNativeEntryTag(uword tag) {
-  if ((tag == kRootTagId) || (tag == kTruncatedTagId)) {
-    return false;
-  }
-  ASSERT(tag != kInvalidTagId);
-  ASSERT(tag != kNumVMTags);
-  ASSERT(tag != kLastTagId);
-  return (tag > kNumVMTags) && !IsRuntimeEntryTag(tag);
+  return (tag > kLastTagId) && !IsRuntimeEntryTag(tag);
 }
 
+
 static RuntimeEntry* runtime_entry_list = NULL;
 
+
 bool VMTag::IsRuntimeEntryTag(uword id) {
   const RuntimeEntry* current = runtime_entry_list;
   while (current != NULL) {