A64: Synchronize with r18084.

src/a64/macro-assembler-a64.cc

Index: src/a64/macro-assembler-a64.cc
diff --git a/src/a64/macro-assembler-a64.cc b/src/a64/macro-assembler-a64.cc
index 7a245ad65ac776592afb2ad7e7e4a33ec65fd6f0..9517be9465767a80bff5476df1c0a4b53f0ff77e 100644
--- a/src/a64/macro-assembler-a64.cc
+++ b/src/a64/macro-assembler-a64.cc
@@ -4024,6 +4024,12 @@ void MacroAssembler::RecordWrite(Register object,
     Check(eq, kWrongAddressOrValuePassedToRecordWrite);
   }
 
+  // Count number of write barriers in generated code.
+  isolate()->counters()->write_barriers_static()->Increment();
+  // TODO(mstarzinger): Dynamic counter missing.
+
+  // First, check if a write barrier is even needed. The tests below
+  // catch stores of smis and stores into the young generation.
   Label done;
 
   if (smi_check == INLINE_SMI_CHECK) {