fix: public api surface fixes + stability markers

- ts-api-guardian will now error if a new public symbol is added with a stability marker (`@stable`, `@experimental`, `@deprecated`)
- DomEventsPlugin and KeyEventsPlugin were removed from public api surface - these classes is an implementation detail
- deprecated BROWSER_PROVIDERS was removed completely
- `@angular/compiler` was removed from the ts-api-guardian check since this package shouldn't contain anything that users need to directly import
- the rest of the api surface was conservatively marked as stable or experimental

BREAKING CHANGES: DomEventsPlugin and KeyEventsPlugin previously exported from core are no longer public - these classes are implementation detail.

Previously deprecated BROWSER_PROVIDERS was completely removed from platform-browser.

Closes #9236
Closes #9235
Ref #9234

modules/@angular/http/http.ts

@@ -179,6 +179,8 @@ export {URLSearchParams} from './src/url_search_params';
  *         useValue: new CookieXSRFStrategy('MY-XSRF-COOKIE-NAME', 'X-MY-XSRF-HEADER-NAME')}])
  *   .catch(err => console.error(err));
  * ```
+ *
+ * @experimental
  */
 export const HTTP_PROVIDERS: any[] = [
   // TODO(pascal): use factory type annotations once supported in DI
@@ -191,6 +193,10 @@ export const HTTP_PROVIDERS: any[] = [
   {provide: XSRFStrategy, useValue: new CookieXSRFStrategy()},
 ];
 
+
+/**
+ * @experimental
+ */
 export function httpFactory(xhrBackend: XHRBackend, requestOptions: RequestOptions): Http {
   return new Http(xhrBackend, requestOptions);
 }
@@ -308,6 +314,8 @@ export const HTTP_BINDINGS = HTTP_PROVIDERS;
  *   }
  * });
  * ```
+ *
+ * @experimental
  */
 export const JSONP_PROVIDERS: any[] = [
   // TODO(pascal): use factory type annotations once supported in DI

modules/@angular/http/src/backends/browser_xhr.ts

@@ -12,6 +12,8 @@ import {Injectable} from '@angular/core';
  * A backend for http that uses the `XMLHttpRequest` browser API.
  *
  * Take care not to evaluate this in non-browser contexts.
+ *
+ * @experimental
  */
 @Injectable()
 export class BrowserXhr {

modules/@angular/http/src/backends/jsonp_backend.ts

@@ -25,6 +25,8 @@ const JSONP_ERR_WRONG_METHOD = 'JSONP requests must use GET request method.';
 
 /**
  * Abstract base class for an in-flight JSONP request.
+ *
+ * @experimental
  */
 export abstract class JSONPConnection implements Connection {
   /**
@@ -143,6 +145,8 @@ export class JSONPConnection_ extends JSONPConnection {
 
 /**
  * A {@link ConnectionBackend} that uses the JSONP strategy of making requests.
+ *
+ * @experimental
  */
 export abstract class JSONPBackend extends ConnectionBackend {}
 

modules/@angular/http/src/backends/xhr_backend.ts

@@ -31,6 +31,8 @@ const XSSI_PREFIX = /^\)\]\}',?\n/;
  *
  * This class would typically not be created or interacted with directly inside applications, though
  * the {@link MockConnection} may be interacted with in tests.
+ *
+ * @experimental
  */
 export class XHRConnection implements Connection {
   request: Request;
@@ -156,6 +158,8 @@ export class XHRConnection implements Connection {
  * Applications can configure custom cookie and header names by binding an instance of this class
  * with different `cookieName` and `headerName` values. See the main HTTP documentation for more
  * details.
+ *
+ * @experimental
  */
 export class CookieXSRFStrategy implements XSRFStrategy {
   constructor(
@@ -193,7 +197,8 @@ export class CookieXSRFStrategy implements XSRFStrategy {
  *   }
  * }
  * ```
- **/
+ * @experimental
+ */
 @Injectable()
 export class XHRBackend implements ConnectionBackend {
   constructor(

modules/@angular/http/src/base_request_options.ts

@@ -40,6 +40,8 @@ import {URLSearchParams} from './url_search_params';
  * console.log('req.method:', RequestMethod[req.method]); // Post
  * console.log('options.url:', options.url); // https://google.com
  * ```
+ *
+ * @experimental
  */
 export class RequestOptions {
   /**
@@ -164,6 +166,8 @@ export class RequestOptions {
  * console.log('options.url:', options.url); // null
  * console.log('req.url:', req.url); // https://google.com
  * ```
+ *
+ * @experimental
  */
 @Injectable()
 export class BaseRequestOptions extends RequestOptions {

modules/@angular/http/src/base_response_options.ts

@@ -40,6 +40,8 @@ import {ResponseOptionsArgs} from './interfaces';
  *
  * console.log('res.json():', res.json()); // Object {name: "Jeff"}
  * ```
+ *
+ * @experimental
  */
 export class ResponseOptions {
   // TODO: ArrayBuffer | FormData | Blob
@@ -155,6 +157,8 @@ export class ResponseOptions {
  * console.log('res.headers.get("framework"):', res.headers.get('framework')); // angular
  * console.log('res.text():', res.text()); // Angular;
  * ```
+ *
+ * @experimental
  */
 @Injectable()
 export class BaseResponseOptions extends ResponseOptions {

modules/@angular/http/src/enums.ts

@@ -8,6 +8,7 @@
 
 /**
  * Supported http methods.
+ * @experimental
  */
 export enum RequestMethod {
   Get,
@@ -23,6 +24,7 @@ export enum RequestMethod {
  * All possible states in which a connection can be, based on
  * [States](http://www.w3.org/TR/XMLHttpRequest/#states) from the `XMLHttpRequest` spec, but with an
  * additional "CANCELLED" state.
+ * @experimental
  */
 export enum ReadyState {
   Unsent,
@@ -36,6 +38,7 @@ export enum ReadyState {
 /**
  * Acceptable response types to be associated with a {@link Response}, based on
  * [ResponseType](https://fetch.spec.whatwg.org/#responsetype) from the Fetch spec.
+ * @experimental
  */
 export enum ResponseType {
   Basic,
@@ -47,6 +50,7 @@ export enum ResponseType {
 
 /**
  * Supported content type to be automatically associated with a {@link Request}.
+ * @experimental
  */
 export enum ContentType {
   NONE,

modules/@angular/http/src/headers.ts

@@ -36,6 +36,8 @@ import {isListLikeIterable, iterateListLike, Map, MapWrapper, StringMapWrapper,
  * var thirdHeaders = new Headers(secondHeaders);
  * console.log(thirdHeaders.get('X-My-Custom-Header')); //'Angular'
  * ```
+ *
+ * @experimental
  */
 export class Headers {
   /** @internal */

modules/@angular/http/src/http.ts

@@ -103,7 +103,8 @@ function mergeOptions(
  * http.get('request-from-mock-backend.json').subscribe((res:Response) => doSomething(res));
  * ```
  *
- **/
+ * @experimental
+ */
 @Injectable()
 export class Http {
   constructor(protected _backend: ConnectionBackend, protected _defaultOptions: RequestOptions) {}
@@ -186,6 +187,10 @@ export class Http {
   }
 }
 
+
+/**
+ * @experimental
+ */
 @Injectable()
 export class Jsonp extends Http {
   constructor(backend: ConnectionBackend, defaultOptions: RequestOptions) {

modules/@angular/http/src/interfaces.ts

@@ -16,11 +16,15 @@ import {URLSearchParams} from './url_search_params';
  *
  * The primary purpose of a `ConnectionBackend` is to create new connections to fulfill a given
  * {@link Request}.
+ *
+ * @experimental
  */
 export abstract class ConnectionBackend { abstract createConnection(request: any): Connection; }
 
 /**
  * Abstract class from which real connections are derived.
+ *
+ * @experimental
  */
 export abstract class Connection {
   readyState: ReadyState;
@@ -28,12 +32,18 @@ export abstract class Connection {
   response: any;  // TODO: generic of <Response>;
 }
 
-/** An XSRFStrategy configures XSRF protection (e.g. via headers) on an HTTP request. */
+/**
+ * An XSRFStrategy configures XSRF protection (e.g. via headers) on an HTTP request.
+ *
+ * @experimental
+ */
 export abstract class XSRFStrategy { abstract configureRequest(req: Request): void; }
 
 /**
  * Interface for options to construct a RequestOptions, based on
  * [RequestInit](https://fetch.spec.whatwg.org/#requestinit) from the Fetch spec.
+ *
+ * @experimental
  */
 export interface RequestOptionsArgs {
   url?: string;
@@ -52,6 +62,8 @@ export interface RequestArgs extends RequestOptionsArgs { url: string; }
 /**
  * Interface for options to construct a Response, based on
  * [ResponseInit](https://fetch.spec.whatwg.org/#responseinit) from the Fetch spec.
+ *
+ * @experimental
  */
 export type ResponseOptionsArgs = {
   // TODO: Support Blob, ArrayBuffer, JSON

modules/@angular/http/src/static_request.ts

@@ -52,6 +52,8 @@ import {URLSearchParams} from './url_search_params';
  *   console.log('people', res.json());
  * });
  * ```
+ *
+ * @experimental
  */
 export class Request {
   /**

modules/@angular/http/src/static_response.ts

@@ -32,6 +32,8 @@ import {isJsObject} from './http_utils';
  * Spec](https://fetch.spec.whatwg.org/#response-class), but is considered a static value whose body
  * can be accessed many times. There are other differences in the implementation, but this is the
  * most significant.
+ *
+ * @experimental
  */
 export class Response {
   /**

modules/@angular/http/src/url_search_params.ts

@@ -32,6 +32,8 @@ function paramParser(rawParams: string = ''): Map<string, string[]> {
  *   - setAll()
  *   - appendAll()
  *   - replaceAll()
+ *
+ * @experimental
  */
 export class URLSearchParams {
   paramsMap: Map<string, string[]>;

modules/@angular/http/testing/mock_backend.ts

@@ -23,7 +23,8 @@ import {Response} from '../src/static_response';
  *
  * Mock Connection to represent a {@link Connection} for tests.
  *
- **/
+ * @experimental
+ */
 export class MockConnection implements Connection {
   // TODO Name `readyState` should change to be more generic, and states could be made to be more
   // descriptive than XHR states.
@@ -141,7 +142,9 @@ export class MockConnection implements Connection {
  * ```
  *
  * This method only exists in the mock implementation, not in real Backends.
- **/
+ *
+ * @experimental
+ */
 @Injectable()
 export class MockBackend implements ConnectionBackend {
   /**