Fix two bugs in the serivce protocol specification

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,
@@ skipping 750 matching lines @@
 ```
   PropertyType optionalProperty [optional];
 ```
 
 If a property can have multiple independent types, we denote this with
 a vertical bar:
 
 ```
   PropertyType1|PropertyType2 complexProperty;
 ```
 

[turnidge, 2015/10/12 16:51:19]

Document parens here.  Something like:

We also allow parentheses in type expressions.  This is useful when a property
is an _Array_ of multiple independent types:

    (PropertyType1|PropertyType2)[]

[Cutch, 2015/10/12 17:40:47]

Done.

 When a string is only permitted to take one of a certain set of values,
 we indicate this by the use of the _enum_ format:
 
 ```
 enum PermittedValues {
   Value1,
   Value2
 }
 ```
 
@@ skipping 675 matching lines @@
   //   TypeParameter
   @Class parameterizedClass [optional];
 
   // The fields of this Instance.
   BoundField[] fields [optional];
 
   // The elements of a List instance.
   //
   // Provided for instance kinds:
   //   List
-  @Instance|Sentinel[] elements [optional];
+  @Instance[]|Sentinel[] elements [optional];

[turnidge, 2015/10/12 16:51:19]

This would mean that we either return a vector of Instances or a vector of
Sentinel.  Neither of those is quite right.

What we are really returning is:

  (@Instance|Sentinel)[]

[Cutch, 2015/10/12 17:40:47]

Done.

 
   // The elements of a List instance.
   //
   // Provided for instance kinds:
   //   Map
   MapAssociation[] associations [optional];
 
   // The bytes of a TypedData instance.
   //
   // The data is provided as a Base64 encoded string.
@@ skipping 651 matching lines @@
   // in a backwards compatible way.
   int minor;
 }
 ```
 
 See [Versioning](#versioning).
 
 ### VM
 
 ```
+class @VM extends Response {
+  // A name identifying this vm. Not guaranteed to be unique.
+  string name;
+}
+```
+
+_@VM_ is a reference to a _VM_ object.
+
+```
 class VM extends Response {
   // Word length on target architecture (e.g. 32, 64).
   int architectureBits;
 
   // The CPU we are generating code for.
   string targetCPU;
 
   // The CPU we are actually running on.
   string hostCPU;
 
@@ skipping 16 matching lines @@
 ## 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.
 
 
 [discuss-list]: https://groups.google.com/a/dartlang.org/forum/#!forum/observatory-discuss