Add an API function to get a debugger stack trace from an error handle.

runtime/vm/debugger.h

Index: runtime/vm/debugger.h
diff --git a/runtime/vm/debugger.h b/runtime/vm/debugger.h
index 8586626aa054bb0119054923c73b2fd7a6871e75..41306474f1b42baced72ffbea50c92445e4e645b 100644
--- a/runtime/vm/debugger.h
+++ b/runtime/vm/debugger.h
@@ -144,6 +144,7 @@ class ActivationFrame : public ZoneAllocated {
   RawLibrary* Library();
   intptr_t TokenPos();
   intptr_t LineNumber();
+  intptr_t ColumnNumber();
   void SetContext(const Context& ctx) { ctx_ = ctx.raw(); }
 
   // Returns true if this frame is for a function that is visible
@@ -196,6 +197,7 @@ class ActivationFrame : public ZoneAllocated {
   intptr_t token_pos_;
   intptr_t pc_desc_index_;
   intptr_t line_number_;
+  intptr_t column_number_;
   intptr_t context_level_;
 
   // Some frames are deoptimized into a side array in order to inspect them.
@@ -309,6 +311,8 @@ class Debugger {
   bool HasBreakpoint(const Function& func);
 
   DebuggerStackTrace* StackTrace();
+  DebuggerStackTrace* UncachedStackTrace();
+  DebuggerStackTrace* StackTraceFrom(const Stacktrace& dart_stacktrace);
 
   RawArray* GetInstanceFields(const Instance& obj);
   RawArray* GetStaticFields(const Class& cls);