chore(lint): remove unused imports (#11923)

This was done automatically by tslint, which can now fix issues it finds.
The fixer is still pending in PR https://github.com/palantir/tslint/pull/1568
Also I have a local bugfix for https://github.com/palantir/tslint/issues/1569
which causes too many imports to be deleted.

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

@@ -10,7 +10,7 @@ import {Injectable} from '@angular/core';
 import {Observable} from 'rxjs/Observable';
 import {Observer} from 'rxjs/Observer';
 
-import {BaseResponseOptions, ResponseOptions} from '../base_response_options';
+import {ResponseOptions} from '../base_response_options';
 import {ReadyState, RequestMethod, ResponseType} from '../enums';
 import {StringWrapper, isPresent} from '../facade/lang';
 import {Connection, ConnectionBackend} from '../interfaces';

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

@@ -8,7 +8,7 @@
 
 import {Injectable} from '@angular/core';
 
-import {isJsObject, isPresent} from '../src/facade/lang';
+import {isPresent} from '../src/facade/lang';
 
 import {ResponseType} from './enums';
 import {Headers} from './headers';

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

@@ -16,7 +16,6 @@ import {RequestMethod} from './enums';
 import {ConnectionBackend, RequestOptionsArgs} from './interfaces';
 import {Request} from './static_request';
 import {Response} from './static_response';
-import {URLSearchParams} from './url_search_params';
 
 function httpRequest(backend: ConnectionBackend, request: Request): Observable<Response> {
   return backend.createConnection(request).response;

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

@@ -6,13 +6,12 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Json, isString} from '../src/facade/lang';
+
 
 import {ResponseOptions} from './base_response_options';
 import {Body} from './body';
 import {ResponseType} from './enums';
 import {Headers} from './headers';
-import {isJsObject} from './http_utils';
 
 
 /**