Make breakpoints on == fire reliably

runtime/vm/intermediate_language_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/intermediate_language.h"
 
 #include "lib/error.h"
@@ skipping 541 matching lines @@
       __ jmp(&equality_done);
     }
   } else {
     // Call stub, load IC data in register. The stub will update ICData if
     // necessary.
     Register ic_data_reg = locs->temp(0).reg();
     ASSERT(ic_data_reg == RBX);  // Stub depends on it.
     __ LoadObject(ic_data_reg, equality_ic_data);
     compiler->GenerateCall(token_pos,
                            &StubCode::EqualityWithNullArgLabel(),
-                           PcDescriptors::kOther,
+                           PcDescriptors::kEqualNull,
                            locs);
     __ Drop(2);
   }
   __ Bind(&check_ne);
   if (kind == Token::kNE) {
     Label true_label, done;
     // Negate the condition: true label returns false and vice versa.
     __ CompareObject(RAX, Bool::True());
     __ j(EQUAL, &true_label, Assembler::kNearJump);
     __ LoadObject(RAX, Bool::True());
@@ skipping 3777 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64