Add exceptionPauseMode to Isolate response in service.md

runtime/vm/service/service.md

 # Dart VM Service Protocol 3.0
 
 > Please post feedback to the [observatory-discuss group][discuss-list]
 
 This document describes of _version 3.0_ of the Dart VM Service Protocol. This
 protocol is used to communicate with a running Dart Virtual Machine.
 
 To use the Service Protocol, start the VM with the *--observe* flag.
 The VM will start a webserver which services protocol requests via WebSocket.
 It is possible to make HTTP (non-WebSocket) requests,
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   // A list of all libraries for this isolate.
   //
   // Guaranteed to be initialized when the IsolateRunnable event fires.
   @Library[] libraries;
 
   // A list of all breakpoints for this isolate.
   Breakpoint[] breakpoints;
 
   // The error that is causing this isolate to exit, if applicable.
   Error error [optional];
+
+  // The current pause on exception mode for this isolate.
+  ExceptionPauseMode exceptionPauseMode;
 }
 ```
 
 An _Isolate_ object provides information about one isolate in the VM.
 
 ### Library
 
 ```
 class @Library extends @Object {
   // The name of this library.
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 ## Revision History
 
 version | comments
 ------- | --------
 1.0 | initial revision
 2.0 | Describe protocol version 2.0.
 3.0 | Describe protocol version 3.0.  Added UnresolvedSourceLocation.  Added Sentinel return to getIsolate.  Add AddedBreakpointWithScriptUri.  Removed Isolate.entry. The type of VM.pid was changed from string to int.  Added VMUpdate events.  Add offset and count parameters to getObject() and offset and count fields to Instance.
 
 
 [discuss-list]: https://groups.google.com/a/dartlang.org/forum/#!forum/observatory-discuss