Fix a variety of service protocol bugs.

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 480 matching lines @@
 Object|Sentinel  getObject(string isolateId,
                            string objectId)
 ```
 
 The _getObject_ RPC is used to lookup an _object_ from some isolate by
 its _id_.
 
 If _objectId_ is a temporary id which has expired, then then _Expired_
 [Sentinel](#sentinel) is returned.
 
-If _objectId_ refers to an object which has been collected by the VM's
+If _objectId_ refers to a heap object which has been collected by the VM's
 garbage collector, then the _Collected_ [Sentinel](#sentinel) is
 returned.
 
+If _objectId_ refers to a non-heap object which has been deleted, then
+the _Collected_ [Sentinel](#sentinel) is returned.
+
 If the object handle has not expired and the object has not been
 collected, then an [Object](#object) will be returned.
 
 ### getStack
 
 ```
 Stack getStack(string isolateId)
 ```
 
 The _getStack_ RPC is used to retrieve the current execution stack and
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 If the variable is being initialized, the _value_ will be the
 _BeingInitialized_ [Sentinel](#sentinel).
 
 If the variable has been optimized out by the compiler, the _value_
 will be the _OptimizedOut_ [Sentinel](#sentinel).
 
 ### Breakpoint
 
 ```
 class Breakpoint extends Object {
+  // A number identifying this breakpoint to the user.
   int breakpointNumber;
+
+  // Has this breakpoint been assigned to a specific program location?
   bool resolved;
+
+  // SourceLocation when breakpoint is resolved, UnresolvedSourceLocation
+  // when a breakpoint is not resolved.
   SourceLocation|UnresolvedSourceLocation location;
 }
 ```
 
 A _Breakpoint_ describes a debugger breakpoint.
 
+A breakpoint is _resolved_ when it has been assigned to a specific
+program location.  A breakpoint my remain unresolved when it is in
+code which has not yet been compiled or in a library which has not
+been loaded (i.e. a deferred library).
+
 ### Class
 
 ```
 class @Class extends @Object {
   // The name of this class.
   string name;
 }
 ```
 
 _@Class_ is a reference to a _Class_.
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   Native,
   Stub,
   Tag,
   Collected
 }
 ```
 
 ### Context
 
 ```
-class @Context {
+class @Context extends @Object {
   // The number of variables in this context.
   int length;
 }
 ```
 
 ```
-class Context {
+class Context extends Object {
   // The number of variables in this context.
   int length;
 
   // The enclosing context for this context.
   Context parent [optional];
 
   // The variables in this context object.
   ContextElement[] variables;
 }
 ```
 
+A _Context_ is a data structure which holds the captured variables for
+some closure.
+
 ### ContextElement
 
 ```
 class ContextElement {
   @Instance|Sentinel value;
 }
 ```
 
 ### Error
 
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   // The parameterized class of a type parameter:
   //
   // Provided for instance kinds:
   //   TypeParameter
   @Class parameterizedClass [optional];
 
 
   // The pattern of a RegExp instance.
   //
+  // The pattern is always an instance of kind String.
+  //
   // Provided for instance kinds:
   //   RegExp
-  String pattern [optional];
+  @Instance pattern [optional];
 }
 ```
 
 _@Instance_ is a reference to an _Instance_.
 
 ```
 class Instance extends Object {
   // What kind of instance is this?
   InstanceKind kind;
 
@@ skipping 62 matching lines @@
   @Instance|Sentinel[] elements [optional];
 
   // 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.
+  //
   // Provided for instance kinds:
   //   Uint8ClampedList
   //   Uint8List
   //   Uint16List
   //   Uint32List
   //   Uint64List
   //   Int8List
   //   Int16List
   //   Int32List
   //   Int64List
   //   Float32List
   //   Float64List
   //   Int32x4List
   //   Float32x4List
   //   Float64x2List
-  int[] bytes [optional];
+  string bytes [optional];
 
   // The function associated with a Closure instance.
   //
   // Provided for instance kinds:
   //   Closure
   @Function closureFunction [optional];
 
   // The context associated with a Closure instance.
   //
   // Provided for instance kinds:
   //   Closure
-  @Function closureContext [optional];
+  @Context closureContext [optional];
 
   // The referent of a MirrorReference instance.
   //
   // Provided for instance kinds:
   //   MirrorReference
   @Instance mirrorReferent [optional];
 
   // The pattern of a RegExp instance.
   //
   // Provided for instance kinds:
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 ## Revision History
 
 version | comments
 ------- | --------
 1.0 draft 1 | initial revision
 1.1 | Describe protocol version 2.0.
 1.2 | Describe protocol version 3.0.  Added UnresolvedSourceLocation.
 
 
 [discuss-list]: https://groups.google.com/a/dartlang.org/forum/#!forum/observatory-discuss