Uses an object pool on x64

runtime/vm/assembler_x64_test.cc

Index: runtime/vm/assembler_x64_test.cc
===================================================================
--- runtime/vm/assembler_x64_test.cc	(revision 26726)
+++ runtime/vm/assembler_x64_test.cc	(working copy)
@@ -2160,6 +2160,7 @@
   ObjectStore* object_store = Isolate::Current()->object_store();
   const Object& obj = Object::ZoneHandle(object_store->smi_class());
   Label fail;
+  __ EnterDartFrame(0);
   __ LoadObject(RAX, obj);
   __ CompareObject(RAX, obj);
   __ j(NOT_EQUAL, &fail);
@@ -2181,9 +2182,11 @@
   __ CompareObject(RCX, smi);
   __ j(NOT_EQUAL, &fail);
   __ movl(RAX, Immediate(1));  // OK
+  __ LeaveFrame(true);
   __ ret();
   __ Bind(&fail);
   __ movl(RAX, Immediate(0));  // Fail.
+  __ LeaveFrame(true);
   __ ret();
 }
 
@@ -2394,12 +2397,14 @@
 
 // Called from assembler_test.cc.
 ASSEMBLER_TEST_GENERATE(StoreIntoObject, assembler) {
+  __ EnterDartFrame(0);
   __ pushq(CTX);
   __ movq(CTX, RDI);
   __ StoreIntoObject(RDX,
                      FieldAddress(RDX, GrowableObjectArray::data_offset()),
                      RSI);
   __ popq(CTX);
+  __ LeaveFrame(true);
   __ ret();
 }