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

runtime/vm/assembler_ia32.h

Index: runtime/vm/assembler_ia32.h
diff --git a/runtime/vm/assembler_ia32.h b/runtime/vm/assembler_ia32.h
index 07088a44fa18b58099c955f07aa14302a7dff9d4..d147296196cdc3fb3ca54362e63e530ce59a010b 100644
--- a/runtime/vm/assembler_ia32.h
+++ b/runtime/vm/assembler_ia32.h
@@ -611,7 +611,8 @@ class Assembler : public ValueObject {
 
   void StoreIntoObject(Register object,  // Object we are storing into.
                        const Address& dest,  // Where we are storing into.
-                       Register value);  // Value we are storing.
+                       Register value,  // Value we are storing.
+                       bool can_value_be_smi = true);
 
   void StoreIntoObjectNoBarrier(Register object,
                                 const Address& dest,
@@ -790,6 +791,11 @@ class Assembler : public ValueObject {
 
   void StoreIntoObjectFilter(Register object, Register value, Label* no_update);
 
+  // Shorter filtering sequence that assumes that value is not a smi.
+  void StoreIntoObjectFilterNoSmi(Register object,
+                                  Register value,
+                                  Label* no_update);
+
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(Assembler);
 };