Specs: More cleanup around the proposed style model to make things more consistent.

sky/specs/apis.md

 APIs
 ====
 
 The Sky core API
 ----------------
 
 ```javascript
 module 'sky:core' {
 
   // EVENTS
@@ skipping 108 matching lines @@
     // Returns a new Array and new Attr instances every time.
     Array<Attr> getAttributes(); // O(N) in number of attributes
 
     readonly attribute ShadowRoot? shadowRoot; // O(1) // returns the shadow root
     Array<ContentElement> getDestinationInsertionPoints(); // O(N) in number of insertion points the node is in
 
     virtual void endTagParsedCallback(); // noop
     virtual void attributeChangeCallback(String name, String? oldValue, String? newValue); // noop
     // TODO(ianh): does a node ever need to know when it's been redistributed?
 
-    readonly attribute StyleDeclarationList style; // O(1)
+    readonly attribute ElementStyleDeclarationList style; // O(1)
     virtual LayoutManagerConstructor getLayoutManager(RenderNode renderNode); // O(1)
       // default implementation looks up the 'display' property and returns the value:
       //   if (renderNode)
       //     return renderNode.getProperty(phDisplay);
       //   return null;
     readonly attribute RenderNode? renderNode; // O(1)
       // this will be null until the first time it is rendered
     void resetLayoutManager(); // O(1)
       // if renderNode is non-null:
       //   sets renderNode.layoutManager to null
@@ skipping 404 matching lines @@
   the core mojo fabric JS API   sky:mojo:fabric:core
   the asyncWait/cancelWait mojo fabric JS API (interface to IPC thread)  sky:mojo:fabric:ipc
   the mojom for the shell, proxying through C++ so that the shell pipe isn't exposed  sky:mojo:shell
   the sky API  sky:core
   the sky debug symbols for private APIs  sky:debug
 ```
 
 TODO(ianh): determine if we want to separate the "this" from the
 Document, especially for Modules, so that exposing a module's element
 doesn't expose the module's exports attribute.