Give structured information about imports and export in the service's library response.

runtime/vm/service/service.md

 # Dart VM Service Protocol 0.0
 
 This document describes _version 0.0_ 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,
 but this does not allow access to VM _events_ and is not documented
@@ skipping 1279 matching lines @@
 
 ```
 class Library extends Object {
   // The name of this library.
   string name;
 
   // The uri of this library.
   string uri;
 
   // A list of the imports for this library.
-  @Library[] imports;
+  LibraryDependency[] dependencies;
 
   // A list of the scripts which constitute this library.
   @Script[] scripts;
 
   // A list of the top-level variables in this library.
   @Field[] variables;
 
   // A list of the top-level functions in this library.
   @Function[] functions;
 
   // A list of all classes in this library.
   @Class[] classes;
 }
 ```
 
 A _Library_ provides information about a Dart language library.
 
+```
+class LibraryDependency {

[turnidge, 2015/05/28 20:10:28]

Note for future reviews... Each type has its own ### section and is added to the
TOC.

I'm updating this in my current cl...

+  // Is this dependency an import (rather than an export)?
+  bool isImport;
+
+  // Is this dependency deferred?
+  bool isDeferred;
+
+  // The prefix of an 'as' import, or null.
+  String prefix;
+
+  // The library being imported or exported.
+  @Library target;
+}
+```
+
+A _LibraryDependency_ provides information about an import or export.
+
 ### List
 
 ```
 class @List extends @Instance {
   // The length of this list.
   int length;
 }
 ```
 
 _@List_ is a reference to a _List_.
@@ skipping 357 matching lines @@
   // A list of isolates running in the VM.
   @Isolate[] isolates
 }
 ```
 
 ## Revision History
 
 version | comments
 ------- | --------
 0.0 | draft