VM: Refactor allocation stats code and remove duplicate code.

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 f08b9d099fe9f79bfa3b827015d7412c86bc84b2..909ebdae35860d78832fc60538cfab66ae11197d 100644
--- a/runtime/vm/assembler_ia32.h
+++ b/runtime/vm/assembler_ia32.h
@@ -880,16 +880,19 @@ class Assembler : public ValueObject {
 
   void UpdateAllocationStats(intptr_t cid,
                              Register temp_reg,
-                             Heap::Space space);
+                             Heap::Space space,
+                             bool inline_isolate = true);
 
   void UpdateAllocationStatsWithSize(intptr_t cid,
                                      Register size_reg,
                                      Register temp_reg,
-                                     Heap::Space space);
+                                     Heap::Space space,
+                                     bool inline_isolate = true);
   void UpdateAllocationStatsWithSize(intptr_t cid,
                                      intptr_t instance_size,
                                      Register temp_reg,
-                                     Heap::Space space);
+                                     Heap::Space space,
+                                     bool inline_isolate = true);
 
   // Inlined allocation of an instance of class 'cls', code has no runtime
   // calls. Jump to 'failure' if the instance cannot be allocated here.