X87: [crankshaft] Support ES6 tail call elimination.

src/crankshaft/x87/lithium-codegen-x87.h

Index: src/crankshaft/x87/lithium-codegen-x87.h
diff --git a/src/crankshaft/x87/lithium-codegen-x87.h b/src/crankshaft/x87/lithium-codegen-x87.h
index 06f2a40469cb29ade03a2253b090ee63a9686072..3719236a403160da63faa514d7834ab43a765981 100644
--- a/src/crankshaft/x87/lithium-codegen-x87.h
+++ b/src/crankshaft/x87/lithium-codegen-x87.h
@@ -219,11 +219,14 @@ class LCodeGen: public LCodeGenBase {
 
   void LoadContextFromDeferred(LOperand* context);
 
-  // Generate a direct call to a known function.  Expects the function
+  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 edi.
   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);