Revert "Never use classic code generator."

src/x64/full-codegen-x64.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2229 matching lines @@
         __ push(FieldOperand(rcx, GlobalObject::kGlobalReceiverOffset));
         EmitCallWithStub(expr);
       } else {
         { PreservePositionScope scope(masm()->positions_recorder());
           VisitForStackValue(prop->obj());
         }
         EmitKeyedCallWithIC(expr, prop->key(), RelocInfo::CODE_TARGET);
       }
     }
   } else {
+    // Call to some other expression.  If the expression is an anonymous
+    // function literal not called in a loop, mark it as one that should
+    // also use the full code generator.
+    FunctionLiteral* lit = fun->AsFunctionLiteral();
+    if (lit != NULL &&
+        lit->name()->Equals(isolate()->heap()->empty_string()) &&
+        loop_depth() == 0) {
+      lit->set_try_full_codegen(true);
+    }
     { PreservePositionScope scope(masm()->positions_recorder());
       VisitForStackValue(fun);
     }
     // Load global receiver object.
     __ movq(rbx, GlobalObjectOperand());
     __ push(FieldOperand(rbx, GlobalObject::kGlobalReceiverOffset));
     // Emit function call.
     EmitCallWithStub(expr);
   }
 
@@ skipping 2070 matching lines @@
   __ ret(0);
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64