Fix runtests-browser in gulp, including RWC, remove into-stream (#17540)

scripts/types/ambient.d.ts

@@ -13,13 +13,5 @@ declare module "gulp-insert" {
     export function transform(cb: (contents: string, file: {path: string, relative: string}) => string): NodeJS.ReadWriteStream; // file is a vinyl file
 }
 
-declare module "into-stream" {
-    function IntoStream(content: string | Buffer | (string | Buffer)[]): NodeJS.ReadableStream;
-    namespace IntoStream {
-        export function obj(content: any): NodeJS.ReadableStream
-    }
-    export = IntoStream;
-}
-
 declare module "sorcery";
 declare module "travis-fold";