Revert of [Atomics] code stubs for atomic operations

src/compiler/code-stub-assembler.h

 // Copyright 2015 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.
 
 #ifndef V8_COMPILER_CODE_STUB_ASSEMBLER_H_
 #define V8_COMPILER_CODE_STUB_ASSEMBLER_H_
 
 #include <map>
 
 // Clients of this interface shouldn't depend on lots of compiler internals.
@@ skipping 373 matching lines @@
     return BitFieldDecode(word32, T::kShift, T::kMask);
   }
 
   Node* BitFieldDecode(Node* word32, uint32_t shift, uint32_t mask);
 
   // Conversions.
   Node* ChangeFloat64ToTagged(Node* value);
   Node* ChangeInt32ToTagged(Node* value);
   Node* TruncateTaggedToFloat64(Node* context, Node* value);
   Node* TruncateTaggedToWord32(Node* context, Node* value);
-  // Truncate to int32 using JavaScript truncation mode.
-  Node* TruncateFloat64ToInt32(Node* value);
 
   // Type conversions.
   // Throws a TypeError for {method_name} if {value} is not coercible to Object,
   // or returns the {value} converted to a String otherwise.
   Node* ToThisString(Node* context, Node* value, char const* method_name);
 
   // String helpers.
   // Load a character from a String (might flatten a ConsString).
   Node* StringCharCodeAt(Node* string, Node* smi_index);
   // Return the single character string with only {code}.
@@ skipping 99 matching lines @@
   // Map of variables to the list of value nodes that have been added from each
   // merge path in their order of merging.
   std::map<Variable::Impl*, std::vector<Node*>> variable_merges_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_CODE_STUB_ASSEMBLER_H_