Fix http://dartbug.com/23578:

runtime/vm/intermediate_language_arm64.cc

Index: runtime/vm/intermediate_language_arm64.cc
diff --git a/runtime/vm/intermediate_language_arm64.cc b/runtime/vm/intermediate_language_arm64.cc
index a26030244a92bae2e97bd595740efed05ece7b92..38edabd49cd408ca9dd2c2f9860d76136042e982 100644
--- a/runtime/vm/intermediate_language_arm64.cc
+++ b/runtime/vm/intermediate_language_arm64.cc
@@ -24,7 +24,6 @@
 namespace dart {
 
 DECLARE_FLAG(bool, emit_edge_counters);
-DECLARE_FLAG(bool, enable_asserts);
 DECLARE_FLAG(int, optimization_counter_threshold);
 DECLARE_FLAG(bool, use_osr);
 
@@ -362,13 +361,13 @@ static void EmitAssertBoolean(Register reg,
   ASSERT(locs->always_calls());
   Label done;
 
-  if (Isolate::Current()->TypeChecksEnabled()) {
+  if (Isolate::Current()->flags().type_checks()) {
     __ CompareObject(reg, Bool::True(), PP);
     __ b(&done, EQ);
     __ CompareObject(reg, Bool::False(), PP);
     __ b(&done, EQ);
   } else {
-    ASSERT(FLAG_enable_asserts);
+    ASSERT(Isolate::Current()->flags().asserts());
     __ CompareObject(reg, Object::null_instance(), PP);
     __ b(&done, NE);
   }