Begin migrating the vm service from a rest-style interface to a json-rpc style interface.

runtime/vm/service/protocol.md

 # Dart VM Service Protocol
 
 NOTE: The service api is still changing rapidly.  If you use the
 service api, expect to encounter non-compatible changes.
 
 Description
 How to start
 JSON
 Websocket
 
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 Some properties returned by the VM Service begin with an underscore
 (<code>_</code>) character.  These properties are called _private
 properties_.  Private properties provide private information about the
 VM's implementation.  Private properties may be added, removed, or
 changed at any time with any release of the VM.  They are provided for
 those tools that need this level of internal access, such as the
 Observatory.
 
 For example, some responses will have the <code>_vmType</code>
-nnnproperty.  This provides the VM-internal type name of an object, and
+property.  This provides the VM-internal type name of an object, and
 is provided only when this type name differs from the
 <code>type</code> property.
 
 ## Events
 
 TODO
 
 ## Catalog of Types
 
 ### <a name="AbstractType"></a>AbstractType
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 | targetCPU | String |
 | hostCPU | String |
 | date | String | kill? |
 | version | String |
 | pid | int |
 | assertsEnabled | bool | TODO: move to features? |
 | typeChecksEnabled | bool | TODO: move to features? |
 | uptime | double | seconds since vm started |
 | "isolates"    | List of [@Isolate](#Isolate)  |