Fix stacktrace crasher bug in the VM and duplicate breakpoint crasher bug.

runtime/lib/stacktrace.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/bootstrap_natives.h"
 #include "vm/exceptions.h"
 #include "vm/object_store.h"
 #include "vm/runtime_entry.h"
 #include "vm/stack_frame.h"
 
 namespace dart {
 
 // Get a full stack trace.
 // Arg0: stack trace object.
 // Return value: String that represents the full stack trace.
 DEFINE_NATIVE_ENTRY(Stacktrace_getFullStacktrace, 1) {
   const Stacktrace& trace =
       Stacktrace::CheckedHandle(arguments->NativeArgAt(0));
   return trace.FullStacktrace();
 }
 
 
 // Get a concise and pertinent stack trace.
 // Arg0: stack trace object.
 // Return value: String that represents the concise and pertinent stack trace.
 DEFINE_NATIVE_ENTRY(Stacktrace_getStacktrace, 1) {
   const Stacktrace& trace =
       Stacktrace::CheckedHandle(arguments->NativeArgAt(0));
-  return String::New(trace.ToCStringInternal(0));
+  intptr_t frame_index = 0;
+  return String::New(trace.ToCStringInternal(&frame_index));

[Jacob, 2014/04/24 20:28:55]

needed to avoid a null ptr exception.

 }
 
 
 static void IterateFrames(const GrowableObjectArray& code_list,
                           const GrowableObjectArray& pc_offset_list) {
   StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
   StackFrame* frame = frames.NextFrame();
   ASSERT(frame != NULL);  // We expect to find a dart invocation frame.
   Code& code = Code::Handle();
   Smi& offset = Smi::Handle();
@@ skipping 50 matching lines @@
   IterateFrames(code_list, pc_offset_list);
   const Array& code_array = Array::Handle(Array::MakeArray(code_list));
   const Array& pc_offset_array =
       Array::Handle(Array::MakeArray(pc_offset_list));
   const Stacktrace& stacktrace = Stacktrace::Handle(
       Stacktrace::New(code_array, pc_offset_array));
   OS::Print("%s\n", stacktrace.ToCString());
 }
 
 }  // namespace dart