Add API to configure debugger pause on exception

runtime/include/dart_debugger_api.h

Index: runtime/include/dart_debugger_api.h
===================================================================
--- runtime/include/dart_debugger_api.h	(revision 8556)
+++ runtime/include/dart_debugger_api.h	(working copy)
@@ -265,7 +265,24 @@
 DART_EXPORT void Dart_SetExceptionThrownHandler(
                             Dart_ExceptionThrownHandler handler);
 
+
+// On which exceptions to pause.
+typedef enum {
+  kNoPauseOnExceptions = 1,
+  kPauseOnUnhandledExceptions,
+  kPauseOnAllExceptions,
+} Dart_ExceptionPauseInfo;
+
 /**
+ * Define on which exceptions the debugger pauses.
+ *
+ * Requires there to be a current isolate.
+ */
+DART_EXPORT Dart_Handle Dart_SetExceptionPauseInfo(
+                            Dart_ExceptionPauseInfo pause_info);
+
+
+/**
  * Returns in \trace the the current stack trace, or NULL if the
  * VM is not paused.
  *