Delete obsolete debug stub

runtime/vm/stub_code_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"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 1853 matching lines @@
   // Load arguments descriptor into R10.
   __ movq(R10, FieldAddress(RBX, ICData::arguments_descriptor_offset()));
   // Now call the static function. The breakpoint handler function
   // ensures that the call target is compiled.
   __ movq(RBX, FieldAddress(RAX, Code::instructions_offset()));
   __ addq(RBX, Immediate(Instructions::HeaderSize() - kHeapObjectTag));
   __ jmp(RBX);
 }
 
 
-//  TOS(0): return address (Dart code).
-void StubCode::GenerateBreakpointReturnStub(Assembler* assembler) {
-  __ EnterStubFrame();
-  __ pushq(RAX);
-  __ CallRuntime(kBreakpointReturnHandlerRuntimeEntry, 0);
-  __ popq(RAX);
-  __ LeaveStubFrame();
-  __ popq(R11);  // discard return address of call to this stub.
-  __ LeaveDartFrame();
-  __ ret();
-}
-
-
 //  RBX: Inline cache data array.
 //  TOS(0): return address (Dart code).
 void StubCode::GenerateBreakpointDynamicStub(Assembler* assembler) {
   __ EnterStubFrame();
   __ pushq(RBX);
   __ CallRuntime(kBreakpointDynamicHandlerRuntimeEntry, 0);
   __ popq(RBX);
   __ LeaveStubFrame();
 
   // Find out which dispatch stub to call.
@@ skipping 295 matching lines @@
 
   __ movq(left, Address(RSP, 2 * kWordSize));
   __ movq(right, Address(RSP, 1 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64