VM: Refactor allocation stats code and remove duplicate code.

runtime/vm/assembler_arm64.h

Index: runtime/vm/assembler_arm64.h
diff --git a/runtime/vm/assembler_arm64.h b/runtime/vm/assembler_arm64.h
index 14685470e8ec52e7d8fe0f238f1ddb09739b327e..32da483f4f8e341ae2c3fddd7d6a52ae2b3de494 100644
--- a/runtime/vm/assembler_arm64.h
+++ b/runtime/vm/assembler_arm64.h
@@ -1380,12 +1380,14 @@ class Assembler : public ValueObject {
 
   void UpdateAllocationStats(intptr_t cid,
                              Register pp,
-                             Heap::Space space);
+                             Heap::Space space,
+                             bool inline_isolate = true);
 
   void UpdateAllocationStatsWithSize(intptr_t cid,
                                      Register size_reg,
                                      Register pp,
-                                     Heap::Space space);
+                                     Heap::Space space,
+                                     bool inline_isolate = true);
 
   // If allocation tracing for |cid| is enabled, will jump to |trace| label,
   // which will allocate in the runtime where tracing occurs.