Allows turning on checked mode on a per-isolate basis

runtime/vm/intrinsifier_arm64.cc

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_ARM64.
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/intrinsifier.h"
 
 #include "vm/assembler.h"
@@ skipping 25 matching lines @@
   ASSERT(field_offset != Class::kNoTypeArguments);
   return field_offset;
 }
 
 
 // Intrinsify only for Smi value and index. Non-smi values need a store buffer
 // update. Array length is always a Smi.
 void Intrinsifier::ObjectArraySetIndexed(Assembler* assembler) {
   Label fall_through;
 
-  if (FLAG_enable_type_checks) {
+  if (Isolate::Current()->TypeChecksEnabled()) {
     const intptr_t type_args_field_offset =
         ComputeObjectArrayTypeArgumentsOffset();
     // Inline simple tests (Smi, null), fallthrough if not positive.
     Label checked_ok;
     __ ldr(R2, Address(SP, 0 * kWordSize));  // Value.
 
     // Null value is valid for any type.
     __ CompareObject(R2, Object::null_object(), PP);
     __ b(&checked_ok, EQ);
 
@@ skipping 80 matching lines @@
 
   __ Bind(&fall_through);
 }
 
 
 // Add an element to growable array if it doesn't need to grow, otherwise
 // call into regular code.
 // On stack: growable array (+1), value (+0).
 void Intrinsifier::GrowableArray_add(Assembler* assembler) {
   // In checked mode we need to type-check the incoming argument.
-  if (FLAG_enable_type_checks) {
+  if (Isolate::Current()->TypeChecksEnabled()) {
     return;
   }
   Label fall_through;
   // R0: Array.
   __ ldr(R0, Address(SP, 1 * kWordSize));
   // R1: length.
   __ ldr(R1, FieldAddress(R0, GrowableObjectArray::length_offset()));
   // R2: data.
   __ ldr(R2, FieldAddress(R0, GrowableObjectArray::data_offset()));
   // R3: capacity.
@@ skipping 1868 matching lines @@
   Isolate* isolate = Isolate::Current();
   __ LoadImmediate(R1, reinterpret_cast<uword>(isolate), kNoPP);
   // Set return value to Isolate::current_tag_.
   __ ldr(R0, Address(R1, Isolate::current_tag_offset()));
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64