[builtins] Migrate Math.abs() to TurboFan builtins.

src/compiler/code-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_ASSEMBLER_H_
 #define V8_COMPILER_CODE_ASSEMBLER_H_
 
 #include <map>
 
 // Clients of this interface shouldn't depend on lots of compiler internals.
@@ skipping 90 matching lines @@
   V(Word32Sar)                             \
   V(Word32Ror)                             \
   V(Word64Or)                              \
   V(Word64And)                             \
   V(Word64Xor)                             \
   V(Word64Shr)                             \
   V(Word64Sar)                             \
   V(Word64Ror)
 
 #define CODE_ASSEMBLER_UNARY_OP_LIST(V) \
+  V(Float64Abs)                         \
   V(Float64Atan)                        \
   V(Float64Atanh)                       \
   V(Float64Cos)                         \
   V(Float64Cosh)                        \
   V(Float64Exp)                         \
   V(Float64Expm1)                       \
   V(Float64Log)                         \
   V(Float64Log1p)                       \
   V(Float64Log2)                        \
   V(Float64Log10)                       \
@@ skipping 312 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_ASSEMBLER_H_