Remove deprecated Megamorphic stub.

runtime/vm/stub_code_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"
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 1242 matching lines @@
     Assembler* assembler) {
   __ Stop("GenerateThreeArgsOptimizedCheckInlineCacheStub");
 }
 
 
 void StubCode::GenerateClosureCallInlineCacheStub(Assembler* assembler) {
   __ Stop("GenerateClosureCallInlineCacheStub");
 }
 
 
-void StubCode::GenerateMegamorphicCallStub(Assembler* assembler) {
-  __ Stop("GenerateMegamorphicCallStub");
-}
-
-
 void StubCode::GenerateZeroArgsUnoptimizedStaticCallStub(Assembler* assembler) {
   GenerateUsageCounterIncrement(assembler, R6);
 #if defined(DEBUG)
   { Label ok;
     // Check that the IC data array has NumArgsTested() == 0.
     // 'NumArgsTested' is stored in the least significant bits of 'state_bits'.
     __ LoadFromOffset(R6, R5, ICData::state_bits_offset() - kHeapObjectTag,
                       kUnsignedWord);
     ASSERT(ICData::NumArgsTestedShift() == 0);  // No shift needed.
     __ andi(R6, R6, ICData::NumArgsTestedMask());
@@ skipping 226 matching lines @@
 
 
 void StubCode::GenerateOptimizedIdenticalWithNumberCheckStub(
     Assembler* assembler) {
   __ Stop("GenerateOptimizedIdenticalWithNumberCheckStub");
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64