Support use of external strings as inputs to LoadCodeUnitsInstr.

runtime/vm/assembler_arm.h

 // Copyright (c) 2013, 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.
 
 #ifndef VM_ASSEMBLER_ARM_H_
 #define VM_ASSEMBLER_ARM_H_
 
 #ifndef VM_ASSEMBLER_H_
 #error Do not include assembler_arm.h directly; use assembler.h instead.
 #endif
@@ skipping 679 matching lines @@
   void LoadClass(Register result, Register object, Register scratch);
   void CompareClassId(Register object, intptr_t class_id, Register scratch);
   void LoadTaggedClassIdMayBeSmi(Register result, Register object);
 
   void LoadWordFromPoolOffset(Register rd, int32_t offset, Condition cond = AL);
   void LoadFromOffset(OperandSize type,
                       Register reg,
                       Register base,
                       int32_t offset,
                       Condition cond = AL);
+  void LoadFieldFromOffset(OperandSize type,
+                           Register reg,
+                           Register base,
+                           int32_t offset,
+                           Condition cond = AL) {
+    LoadFromOffset(type, reg, base, offset - kHeapObjectTag, cond);
+  }
   void StoreToOffset(OperandSize type,
                      Register reg,
                      Register base,
                      int32_t offset,
                      Condition cond = AL);
   void LoadSFromOffset(SRegister reg,
                        Register base,
                        int32_t offset,
                        Condition cond = AL);
   void StoreSToOffset(SRegister reg,
@@ skipping 331 matching lines @@
                                   Register value,
                                   Label* no_update);
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(Assembler);
 };
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_ARM_H_