Use VM tag in profile and add stack trace trie

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 380565bc664165f06ac37d35032b30488288b1c4..d4c3778193faa61bcb922f73f558005938acf9a2 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -40,6 +40,7 @@
 #include "vm/scopes.h"
 #include "vm/stack_frame.h"
 #include "vm/symbols.h"
+#include "vm/tags.h"
 #include "vm/timer.h"
 #include "vm/unicode.h"
 
@@ -7369,8 +7370,9 @@ void Script::Tokenize(const String& private_key) const {
     // Already tokenized.
     return;
   }
-
+  Isolate* isolate = Isolate::Current();

[siva, 2014/03/18 00:05:20]

Please hoist this up as the first line and use
tkns = TokenStream::Handle(isolate, tokens());

[Cutch, 2014/03/18 14:39:19]

Done.

   // Get the source, scan and allocate the token stream.
+  VMTagScope tagScope(isolate, VMTag::kCompileTagId);
   TimerScope timer(FLAG_compiler_stats, &CompilerStats::scanner_timer);
   const String& src = String::Handle(Source());

[siva, 2014/03/18 00:05:20]

Now that we have grabbed the isolate:
src = String::Handle(isolate, Source());

[Cutch, 2014/03/18 14:39:19]

Done.

   Scanner scanner(src, private_key);