Make the segfault handler attempt to symbolize Dart frames.

runtime/bin/platform_macos.cc

 // Copyright (c) 2012, 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 "platform/globals.h"
 #if defined(TARGET_OS_MACOS)
 
 #include "bin/platform.h"
 
 #if !TARGET_OS_IOS
@@ skipping 41 matching lines @@
     return false;
   }
   if (sigaddset(&act.sa_mask, SIGPROF) != 0) {
     perror("sigaddset() failed");
     return false;
   }
   if (sigaction(SIGSEGV, &act, NULL) != 0) {
     perror("sigaction() failed.");
     return false;
   }
+  if (sigaction(SIGTRAP, &act, NULL) != 0) {
+    perror("sigaction() failed.");
+    return false;
+  }
   return true;
 }
 
 
 int Platform::NumberOfProcessors() {
   int32_t cpus = -1;
   size_t cpus_length = sizeof(cpus);
   if (sysctlbyname("hw.logicalcpu", &cpus, &cpus_length, NULL, 0) == 0) {
     return cpus;
   } else {
@@ skipping 79 matching lines @@
 
 
 void Platform::Exit(int exit_code) {
   exit(exit_code);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)