PPC: [crankshaft] Support ES6 tail call elimination.

src/crankshaft/ppc/lithium-codegen-ppc.h

Index: src/crankshaft/ppc/lithium-codegen-ppc.h
diff --git a/src/crankshaft/ppc/lithium-codegen-ppc.h b/src/crankshaft/ppc/lithium-codegen-ppc.h
index 1b72bf82dc26cb81aa49df64d55bbe50316223ee..28f168036c8c27cae1ab76ddc5290c72a4df9118 100644
--- a/src/crankshaft/ppc/lithium-codegen-ppc.h
+++ b/src/crankshaft/ppc/lithium-codegen-ppc.h
@@ -194,11 +194,14 @@ class LCodeGen : public LCodeGenBase {
   void CallRuntimeFromDeferred(Runtime::FunctionId id, int argc,
                                LInstruction* instr, LOperand* context);
 
+  void PrepareForTailCall(const ParameterCount& actual, Register scratch1,
+                          Register scratch2, Register scratch3);
+
   // Generate a direct call to a known function.  Expects the function
   // to be in r4.
   void CallKnownFunction(Handle<JSFunction> function,
                          int formal_parameter_count, int arity,
-                         LInstruction* instr);
+                         bool is_tail_call, LInstruction* instr);
 
   void RecordSafepointWithLazyDeopt(LInstruction* instr,
                                     SafepointMode safepoint_mode);