Shorter TryAllocate instruction sequence on ARM/ARM64/MIPS.

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 319 matching lines @@
 
   // Debugging and bringup support.
   void Stop(const char* message);
   void Unimplemented(const char* message);
   void Untested(const char* message);
   void Unreachable(const char* message);
 
   static void InitializeMemoryWithBreakpoints(uword data, intptr_t length);
 
   void Comment(const char* format, ...) PRINTF_ATTRIBUTE(2, 3);
+  static bool EmittingComments();
 
   const Code::Comments& GetCodeComments() const;
 
   static const char* RegisterName(Register reg);
 
   static const char* FpuRegisterName(FpuRegister reg);
 
   // Data-processing instructions.
   void and_(Register rd, Register rn, Operand o, Condition cond = AL);
 
@@ skipping 604 matching lines @@
                                   Register value,
                                   Label* no_update);
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(Assembler);
 };
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_ARM_H_