[turbofan] JSCreateClosure doesn't have any JS observable side effects.

src/compiler/js-operator.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/js-operator.h"
 
 #include <limits>
 
 #include "src/base/lazy-instance.h"
 #include "src/compiler/opcodes.h"
@@ skipping 1046 matching lines @@
       IrOpcode::kJSCreateArray, Operator::kNoProperties,  // opcode
       "JSCreateArray",                                    // name
       value_input_count, 1, 1, 1, 1, 2,                   // counts
       parameters);                                        // parameter
 }
 
 const Operator* JSOperatorBuilder::CreateClosure(
     Handle<SharedFunctionInfo> shared_info, VectorSlotPair const& feedback,
     PretenureFlag pretenure) {
   CreateClosureParameters parameters(shared_info, feedback, pretenure);
-  return new (zone()) Operator1<CreateClosureParameters>(  // --
-      IrOpcode::kJSCreateClosure, Operator::kNoThrow,      // opcode
-      "JSCreateClosure",                                   // name
-      0, 1, 1, 1, 1, 0,                                    // counts
-      parameters);                                         // parameter
+  return new (zone()) Operator1<CreateClosureParameters>(   // --
+      IrOpcode::kJSCreateClosure, Operator::kEliminatable,  // opcode
+      "JSCreateClosure",                                    // name
+      0, 1, 1, 1, 1, 0,                                     // counts
+      parameters);                                          // parameter
 }
 
 const Operator* JSOperatorBuilder::CreateLiteralArray(
     Handle<ConstantElementsPair> constant_elements, int literal_flags,
     int literal_index, int number_of_elements) {
   CreateLiteralParameters parameters(constant_elements, number_of_elements,
                                      literal_flags, literal_index);
   return new (zone()) Operator1<CreateLiteralParameters>(        // --
       IrOpcode::kJSCreateLiteralArray, Operator::kNoProperties,  // opcode
       "JSCreateLiteralArray",                                    // name
@@ skipping 68 matching lines @@
   return new (zone()) Operator1<Handle<ScopeInfo>>(               // --
       IrOpcode::kJSCreateScriptContext, Operator::kNoProperties,  // opcode
       "JSCreateScriptContext",                                    // name
       1, 1, 1, 1, 1, 2,                                           // counts
       scope_info);                                                // parameter
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8