PPC: [crankshaft] Fixing ES6 tail call elimination.

src/crankshaft/ppc/lithium-ppc.h

Index: src/crankshaft/ppc/lithium-ppc.h
diff --git a/src/crankshaft/ppc/lithium-ppc.h b/src/crankshaft/ppc/lithium-ppc.h
index a633fda12d0ab418fd0a0c10f8eb70330a76857d..7d105b20626e6cfc7361dc48df76a62f002d0b3d 100644
--- a/src/crankshaft/ppc/lithium-ppc.h
+++ b/src/crankshaft/ppc/lithium-ppc.h
@@ -220,6 +220,13 @@ 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(); }
@@ -254,6 +261,8 @@ 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_;