Adds streams-lib polyfill and exports ReadableStream from shared/util.

Added test for ReadableStream.

Adds ref-implementation license-header in streams-lib
and change gulp task to copy external/streams/ in build/
external/streams/ and build/dist/external/streams folder.

Adds README.md and LICENSE.md

.eslintignore

@@ -8,6 +8,7 @@ external/webL10n/
 external/cmapscompress/
 external/builder/fixtures/
 external/builder/fixtures_esprima/
+external/streams/
 src/shared/cffStandardStrings.js
 src/shared/fonts_utils.js
 test/tmp/

external/streams/LICENSE.md

@@ -0,0 +1,21 @@
+# WHATWG Streams Reference Implementation Licensing
+
+For the reference implementation and tests for the WHATWG Streams Standard.
+
+This code is dual-licensed under CC0 and the MIT license. You can choose which one you want to use.
+
+## CC0
+
+To the extent possible under law, the authors have dedicated all copyright and related and neighboring rights to this software to the public domain worldwide. This software is distributed without any warranty.
+
+You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see https://creativecommons.org/publicdomain/zero/1.0/.
+
+## MIT
+
+Copyright (c) 2013–2015 Streams Standard Reference Implementation Authors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

external/streams/README.md

@@ -0,0 +1,9 @@
+# Streams API polyfill for PDF.js
+
+This folder contains streams-lib.js file that works as a polyfill for `Streams API
+in PDF.js` project.
+
+## Steps to create streams-lib.js file
+
+- Fork [Streams API](https://github.com/whatwg/streams/tree/master/reference-implementation) reference implementation.
+- Bundle and port to es5 ref-implementation files using webpack to create commonjs module.