Use shorter write-barrier filtering sequence when value is known to be non-smi.

runtime/vm/assembler.h

Index: runtime/vm/assembler.h
diff --git a/runtime/vm/assembler.h b/runtime/vm/assembler.h
index 200716a1d02fc32627fa1b282b5145d3ec8762a4..65f9cfd378858bb58aca98e2b1851d97e527e011 100644
--- a/runtime/vm/assembler.h
+++ b/runtime/vm/assembler.h
@@ -196,6 +196,12 @@ class AssemblerBuffer : public ValueObject {
   friend class AssemblerFixup;
 };
 
+
+enum ValueSminess {

[Ivan Posva, 2013/03/22 04:11:35]

You need to get a better name for this enum or just use a boolean.
Why do I think it is OK to use a boolean instead in this case: The value is not
set as a constant anywhere, it is always set using the result of a function
which has a Yes/No meaning.

[Vyacheslav Egorov (Google), 2013/03/22 11:22:50]

Killed enum, using boolean instead.

+  kValueCanBeSmi,
+  kValueIsNotSmi
+};
+
 }  // namespace dart