Add functionality to get full stack trace when exceptions are thrown.

runtime/vm/exceptions.cc

Index: runtime/vm/exceptions.cc
===================================================================
--- runtime/vm/exceptions.cc	(revision 19025)
+++ runtime/vm/exceptions.cc	(working copy)
@@ -203,13 +203,30 @@
   Stacktrace& stacktrace = Stacktrace::Handle();
   if (pc_offset_list.Length() != 0) {
     if (existing_stacktrace.IsNull()) {
-      stacktrace = Stacktrace::New(func_list, code_list, pc_offset_list);
+      const Array& func_array = Array::Handle(Array::MakeArray(func_list));
+      const Array& code_array = Array::Handle(Array::MakeArray(code_list));
+      const Array& pc_offset_array =
+          Array::Handle(Array::MakeArray(pc_offset_list));
+
+      stacktrace = Stacktrace::New(func_array, code_array, pc_offset_array);
     } else {
       stacktrace ^= existing_stacktrace.raw();
       stacktrace.Append(func_list, code_list, pc_offset_list);
+      // Since we are re throwing and appending to the existing stack trace
+      // we clear out the catch trace collected in the existing stack trace
+      // as that trace will not be valid anymore.
+      stacktrace.SetCatchStacktrace(Object::empty_array(),
+                                    Object::empty_array(),
+                                    Object::empty_array());
     }
   } else {
     stacktrace ^= existing_stacktrace.raw();
+    // Since we are re throwing the existing stack trace
+    // we clear out the catch trace collected in it
+    // as that trace will not be valid anymore.
+    stacktrace.SetCatchStacktrace(Object::empty_array(),
+                                  Object::empty_array(),
+                                  Object::empty_array());
   }
   if (FLAG_print_stacktrace_at_throw) {
     OS::Print("Exception '%s' thrown:\n", exception.ToCString());