Revert r40623, "Refactor bigint _sqrTo in preparation of intrinsification."

runtime/vm/intrinsifier_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intrinsifier.h"
 
 #include "vm/assembler.h"
@@ skipping 809 matching lines @@
                      FieldAddress(RCX, Bigint::digits_offset()), RAX, false);
   __ ret();
 }
 
 
 void Intrinsifier::Bigint_mulAdd(Assembler* assembler) {
   // TODO(regis): Implement.
 }
 
 
-void Intrinsifier::Bigint_sqrAdd(Assembler* assembler) {
-  // TODO(regis): Implement.
-}
-
-
 // Check if the last argument is a double, jump to label 'is_smi' if smi
 // (easy to convert to double), otherwise jump to label 'not_double_smi',
 // Returns the last argument in RAX.
 static void TestLastArgumentIsDouble(Assembler* assembler,
                                      Label* is_smi,
                                      Label* not_double_smi) {
   __ movq(RAX, Address(RSP, + 1 * kWordSize));
   __ testq(RAX, Immediate(kSmiTagMask));
   __ j(ZERO, is_smi, Assembler::kNearJump);  // Jump if Smi.
   __ CompareClassId(RAX, kDoubleCid);
@@ skipping 713 matching lines @@
   // Set return value to Isolate::current_tag_.
   __ movq(RAX, Address(RBX, Isolate::current_tag_offset()));
   __ ret();
 }
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64