Fix for 3303 MultithreadedParallelIsolates has a race condition.

src/arm/macro-assembler-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #include "v8.h"
 
 #if V8_TARGET_ARCH_ARM
 
@@ skipping 892 matching lines @@
 
 
 void MacroAssembler::Prologue(PrologueFrameMode frame_mode) {
   if (frame_mode == BUILD_STUB_FRAME) {
     PushFixedFrame();
     Push(Smi::FromInt(StackFrame::STUB));
     // Adjust FP to point to saved FP.
     add(fp, sp, Operand(StandardFrameConstants::kFixedFrameSizeFromFp));
   } else {
     PredictableCodeSizeScope predictible_code_size_scope(
-        this, kNoCodeAgeSequenceLength * Assembler::kInstrSize);
+        this, kNoCodeAgeSequenceLength);
     // The following three instructions must remain together and unmodified
     // for code aging to work properly.
     if (isolate()->IsCodePreAgingActive()) {
       // Pre-age the code.
       Code* stub = Code::GetPreAgedCodeAgeStub(isolate());
       add(r0, pc, Operand(-8));
       ldr(pc, MemOperand(pc, -4));
       emit_code_stub_address(stub);
     } else {
       PushFixedFrame(r1);
@@ skipping 3144 matching lines @@
     sub(result, result, Operand(dividend));
   }
   if (ms.shift() > 0) mov(result, Operand(result, ASR, ms.shift()));
   add(result, result, Operand(dividend, LSR, 31));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM