Shorter TryAllocate instruction sequence on ARM/ARM64/MIPS.

runtime/vm/assembler_ia32.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_IA32_H_
 #define VM_ASSEMBLER_IA32_H_
 
 #ifndef VM_ASSEMBLER_H_
 #error Do not include assembler_ia32.h directly; use assembler.h instead.
 #endif
@@ skipping 803 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);
 
   // Smis that do not fit into 17 bits (16 bits of payload) are unsafe.
   static bool IsSafe(const Object& object) {
     return !object.IsSmi() ||
         Utils::IsInt(17, reinterpret_cast<intptr_t>(object.raw()));
   }
@@ skipping 82 matching lines @@
 }
 
 
 inline void Assembler::EmitOperandSizeOverride() {
   EmitUint8(0x66);
 }
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_IA32_H_