[crankshaft] Fixing ES6 tail call elimination.

src/crankshaft/arm/lithium-arm.h

Index: src/crankshaft/arm/lithium-arm.h
diff --git a/src/crankshaft/arm/lithium-arm.h b/src/crankshaft/arm/lithium-arm.h
index 747a8f52d4d36bb19a7084d9557f901c32bd7ff7..18a05cf68a9ed1c29257bb9aafe9d946c2170594 100644
--- a/src/crankshaft/arm/lithium-arm.h
+++ b/src/crankshaft/arm/lithium-arm.h
@@ -224,6 +224,13 @@ class LInstruction : public ZoneObject {
   void MarkAsCall() { bit_field_ = IsCallBits::update(bit_field_, true); }
   bool IsCall() const { return IsCallBits::decode(bit_field_); }
 
+  void MarkAsSyntacticTailCall() {
+    bit_field_ = IsSyntacticTailCallBits::update(bit_field_, true);
+  }
+  bool IsSyntacticTailCall() const {
+    return IsSyntacticTailCallBits::decode(bit_field_);
+  }
+
   // Interface to the register allocator and iterators.
   bool ClobbersTemps() const { return IsCall(); }
   bool ClobbersRegisters() const { return IsCall(); }
@@ -258,6 +265,8 @@ class LInstruction : public ZoneObject {
   virtual LOperand* TempAt(int i) = 0;
 
   class IsCallBits: public BitField<bool, 0, 1> {};
+  class IsSyntacticTailCallBits : public BitField<bool, IsCallBits::kNext, 1> {
+  };
 
   LEnvironment* environment_;
   SetOncePointer<LPointerMap> pointer_map_;