Add StackTrace.current getter.

runtime/lib/stacktrace.cc

Index: runtime/lib/stacktrace.cc
diff --git a/runtime/lib/stacktrace.cc b/runtime/lib/stacktrace.cc
index 6175b24b4d18d841ce132233347e27e3053439a3..7b793141f2c5f0de3c120a6b3abc85ea48bbb399 100644
--- a/runtime/lib/stacktrace.cc
+++ b/runtime/lib/stacktrace.cc
@@ -11,7 +11,8 @@
 namespace dart {
 
 static void IterateFrames(const GrowableObjectArray& code_list,
-                          const GrowableObjectArray& pc_offset_list) {
+                          const GrowableObjectArray& pc_offset_list,
+                          int skip_frames) {
   StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
   StackFrame* frame = frames.NextFrame();
   ASSERT(frame != NULL);  // We expect to find a dart invocation frame.
@@ -19,33 +20,49 @@ static void IterateFrames(const GrowableObjectArray& code_list,
   Smi& offset = Smi::Handle();
   while (frame != NULL) {
     if (frame->IsDartFrame()) {
-      code = frame->LookupDartCode();
-      offset = Smi::New(frame->pc() - code.EntryPoint());
-      code_list.Add(code);
-      pc_offset_list.Add(offset);
+      if (skip_frames > 0) {
+        skip_frames--;
+      } else {
+        code = frame->LookupDartCode();
+        offset = Smi::New(frame->pc() - code.EntryPoint());
+        code_list.Add(code);
+        pc_offset_list.Add(offset);
+      }
     }
     frame = frames.NextFrame();
   }
 }
 
-
-// An utility method for convenient printing of dart stack traces when
-// inside 'gdb'. Note: This function will only work when there is a
-// valid exit frame information. It will not work when a breakpoint is
-// set in dart code and control is got inside 'gdb' without going through
-// the runtime or native transition stub.
-void _printCurrentStacktrace() {
+// Creates a Stacktrace object from the current stack.
+//
+// Skips the first skip_frames Dart frames.
+static const Stacktrace& GetCurrentStacktrace(int skip_frames) {
   const GrowableObjectArray& code_list =
       GrowableObjectArray::Handle(GrowableObjectArray::New());
   const GrowableObjectArray& pc_offset_list =
       GrowableObjectArray::Handle(GrowableObjectArray::New());
-  IterateFrames(code_list, pc_offset_list);
+  IterateFrames(code_list, pc_offset_list, skip_frames);
   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));
+  return stacktrace;
+}
+
+// An utility method for convenient printing of dart stack traces when
+// inside 'gdb'. Note: This function will only work when there is a
+// valid exit frame information. It will not work when a breakpoint is
+// set in dart code and control is got inside 'gdb' without going through
+// the runtime or native transition stub.
+void _printCurrentStacktrace() {
+  const Stacktrace& stacktrace = GetCurrentStacktrace(0);
   OS::PrintErr("=== Current Trace:\n%s===\n", stacktrace.ToCString());
 }
 
+DEFINE_NATIVE_ENTRY(StackTrace_current, 0) {
+  const Stacktrace& stacktrace = GetCurrentStacktrace(1);
+  return stacktrace.raw();
+}
+
 }  // namespace dart