Support optimization of named function literals.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index fe71ff53d6796c6eeab380d4f44222aea8c3852d..e3ae8d83c5ad5fe427163db1d7cef67af7a03dca 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -2678,6 +2678,12 @@ void LCodeGen::DoPushArgument(LPushArgument* instr) {
 }
 
 
+void LCodeGen::DoThisFunction(LThisFunction* instr) {
+  Register result = ToRegister(instr->result());
+  __ movq(result, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
+}
+
+
 void LCodeGen::DoContext(LContext* instr) {
   Register result = ToRegister(instr->result());
   __ movq(result, rsi);