Fix for 3303 MultithreadedParallelIsolates has a race condition.

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index 5b5b7ea52c17404350b7e09f04a743d5eb47a67c..789dac6567344b348a076af8aaea0f1339b26893 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -910,7 +910,7 @@ void MacroAssembler::Prologue(PrologueFrameMode frame_mode) {
     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()) {