Add function for one-time stop at function entry

runtime/include/dart_debugger_api.h

Index: runtime/include/dart_debugger_api.h
===================================================================
--- runtime/include/dart_debugger_api.h	(revision 17321)
+++ runtime/include/dart_debugger_api.h	(working copy)
@@ -222,9 +222,9 @@
 
 
 /**
- * Sets a breakpoint at the entry of the given function. If class_name
- * is the empty string, looks for a library function with the given
- * name.
+ * Sets a one-time breakpoint at the entry of the given function.
+ * If class_name is the empty string, looks for a library function
+ * with the given name.
  *
  * Requires there to be a current isolate.
  *
@@ -241,6 +241,21 @@
 
 
 /**
+ * Sets a breakpoint at the entry of the given function. If class_name
+ * is the empty string, looks for a library function with the given
+ * name.
+ *
+ * Requires there to be a current isolate.
+ *
+ * \return A handle to the True object if no error occurs.
+ */
+DART_EXPORT Dart_Handle Dart_OneTimeBreakAtEntry(
+                            Dart_Handle library,
+                            Dart_Handle class_name,
+                            Dart_Handle function_name);
+
+
+/**
  * DEPRECATED -- use Dart_RemoveBreakpoint instead.
  *
  * Deletes the given \breakpoint.