Update css types

Make all of the AtRule interfaces inherit from Node.
Break out StyleRules from Stylesheet, as it's own type. This is useful when using rework, which is only given the Stylesheet.stylesheet object.
Change StyleRules proeprty rules to be mandatory. It is always set.

types/css/index.d.ts

@@ -112,7 +112,7 @@ export interface Comment extends Node {
 /** 
  * The @charset at-rule. 
  */
-export interface Charset {
+export interface Charset extends Node {
     /** The part following @charset. */
     charset?: string;
 }
@@ -120,7 +120,7 @@ export interface Charset {
 /**
  * The @custom-media at-rule 
  */
-export interface CustomMedia {
+export interface CustomMedia extends Node {
     /** The ---prefixed name. */
     name?: string;
     /** The part following the name. */
@@ -130,7 +130,7 @@ export interface CustomMedia {
 /**
  * The @document at-rule.
  */
-export interface Document {
+export interface Document extends Node {
     /** The part following @document. */
     document?: string;
     /** The vendor prefix in @document, or undefined if there is none. */
@@ -142,7 +142,7 @@ export interface Document {
 /**
  * The @font-face at-rule.
  */
-export interface FontFace {
+export interface FontFace extends Node {
     /** Array of nodes with the types declaration and comment. */
     declarations?: Array<Declaration | Comment>;
 }
@@ -150,7 +150,7 @@ export interface FontFace {
 /**
  * The @host at-rule.
  */
-export interface Host {
+export interface Host extends Node {
     /** Array of nodes with the types rule, comment and any of the at-rule types. */
     rules?: Array<Rule | Comment | AtRule>;
 }
@@ -158,7 +158,7 @@ export interface Host {
 /**
  * The @import at-rule.
  */
-export interface Import {
+export interface Import extends Node {
     /** The part following @import. */
     import?: string;
 }
@@ -166,7 +166,7 @@ export interface Import {
 /**
  * The @keyframes at-rule.
  */
-export interface KeyFrames {
+export interface KeyFrames extends Node {
     /** The name of the keyframes rule. */
     name?: string;
     /** The vendor prefix in @keyframes, or undefined if there is none. */
@@ -175,7 +175,7 @@ export interface KeyFrames {
     keyframes?: Array<KeyFrame | Comment>;
 }
 
-export interface KeyFrame {
+export interface KeyFrame extends Node {
     /** The list of "selectors" of the keyframe rule, split on commas. Each “selector” is trimmed from whitespace. */
     values?: Array<string>;
     /** Array of nodes with the types declaration and comment. */
@@ -185,7 +185,7 @@ export interface KeyFrame {
 /**
  * The @media at-rule.
  */
-export interface Media {
+export interface Media extends Node {
     /** The part following @media. */
     media?: string;
     /** Array of nodes with the types rule, comment and any of the at-rule types. */
@@ -195,7 +195,7 @@ export interface Media {
 /**
  * The @namespace at-rule.
  */
-export interface Namespace {
+export interface Namespace extends Node {
     /** The part following @namespace. */
     namespace?: string;
 }
@@ -203,7 +203,7 @@ export interface Namespace {
 /**
  * The @page at-rule.
  */
-export interface Page {
+export interface Page extends Node {
     /** The list of selectors of the rule, split on commas. Each selector is trimmed from whitespace and comments. */
     selectors?: Array<string>;
     /** Array of nodes with the types declaration and comment. */
@@ -213,7 +213,7 @@ export interface Page {
 /**
  * The @supports at-rule.
  */
-export interface Supports {
+export interface Supports extends Node {
     /** The part following @supports. */
     supports?: string;
     /** Array of nodes with the types rule, comment and any of the at-rule types. */
@@ -223,16 +223,21 @@ export interface Supports {
 /** All at-rules. */
 export type AtRule = Charset | CustomMedia | Document | FontFace | Host | Import | KeyFrames | Media | Namespace | Page | Supports;
 
+/**
+ * A collection of rules
+ */
+export interface StyleRules {
+    /** Array of nodes with the types rule, comment and any of the at-rule types. */
+    rules: Array<Rule | Comment | AtRule>;
+    /** Array of Errors. Errors collected during parsing when option silent is true. */
+    parsingErrors?: Array<ParserError>
+}
+
 /** 
  * The root node returned by css.parse. 
  */
 export interface Stylesheet extends Node {
-    stylesheet?: {
-        /** Array of nodes with the types rule, comment and any of the at-rule types. */
-        rules?: Array<Rule | Comment | AtRule>;
-        /** Array of Errors. Errors collected during parsing when option silent is true. */
-        parsingErrors?: Array<ParserError>
-    };
+    stylesheet?: StyleRules;
 }
 
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