Resubmit reverted r40623 unchanged after GC issue fixed.

runtime/vm/intrinsifier_arm64.cc

 // Copyright (c) 2014, 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_ARM64.
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/intrinsifier.h"
 
 #include "vm/assembler.h"
@@ skipping 788 matching lines @@
   __ StoreIntoObject(R1, FieldAddress(R1, Bigint::digits_offset()), R0, 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 R0.
 static void TestLastArgumentIsDouble(Assembler* assembler,
                                      Label* is_smi,
                                      Label* not_double_smi) {
   __ ldr(R0, Address(SP, 0 * kWordSize));
   __ tsti(R0, kSmiTagMask);
   __ b(is_smi, EQ);
   __ CompareClassId(R0, kDoubleCid, kNoPP);
@@ skipping 708 matching lines @@
   Isolate* isolate = Isolate::Current();
   __ LoadImmediate(R1, reinterpret_cast<uword>(isolate), kNoPP);
   // Set return value to Isolate::current_tag_.
   __ ldr(R0, Address(R1, Isolate::current_tag_offset()));
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64