Remove internal `utf8` utility

Summary:
As requested by davidaurelio in https://github.com/mathiasbynens/utf8.js/issues/17#issuecomment-312500535, this makes it possible for developers to use the `utf8` package from npm in combination with React Native.

Ref. https://github.com/mathiasbynens/utf8.js/issues/17
Closes https://github.com/facebook/react-native/pull/17146

Differential Revision: D6765030

Pulled By: hramos

fbshipit-source-id: dda9b3255618470aea2e32c5ba3cf1325e2ec997

Libraries/Utilities/__tests__/utf8-test.js

@@ -1,63 +0,0 @@
-/**
- * Copyright (c) 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @emails oncall+react_native
- */
-
-'use strict';
-
-const {encode} = require('../utf8');
-
-describe('UTF-8 encoding:', () => {
-   it('can encode code points < U+80', () => {
-     const arrayBuffer = encode('\u0000abcDEF\u007f');
-     expect(new Uint8Array(arrayBuffer)).toEqual(
-       new Uint8Array([0x00, 0x61, 0x62, 0x63, 0x44, 0x45, 0x46, 0x7f]));
-   });
-
-   it('can encode code points < U+800', () => {
-     const arrayBuffer = encode('\u0080\u0548\u07ff');
-     expect(new Uint8Array(arrayBuffer)).toEqual(
-       new Uint8Array([0xc2, 0x80, 0xd5, 0x88, 0xdf, 0xbf]));
-   });
-
-   it('can encode code points < U+10000', () => {
-     const arrayBuffer = encode('\u0800\uac48\uffff');
-     expect(new Uint8Array(arrayBuffer)).toEqual(
-       new Uint8Array([0xe0, 0xa0, 0x80, 0xea, 0xb1, 0x88, 0xef, 0xbf, 0xbf]));
-   });
-
-   it('can encode code points in the Supplementary Planes (surrogate pairs)', () => {
-     const arrayBuffer = encode([
-       '\ud800\udc00',
-       '\ud800\ude89',
-       '\ud83d\ude3b',
-       '\udbff\udfff'
-     ].join(''));
-     expect(new Uint8Array(arrayBuffer)).toEqual(
-       new Uint8Array([
-         0xf0, 0x90, 0x80, 0x80,
-         0xf0, 0x90, 0x8a, 0x89,
-         0xf0, 0x9f, 0x98, 0xbb,
-         0xf4, 0x8f, 0xbf, 0xbf,
-       ])
-     );
-   });
-
-   it('allows for stray high surrogates', () => {
-     const arrayBuffer = encode(String.fromCharCode(0x61, 0xd8c6, 0x62));
-     expect(new Uint8Array(arrayBuffer)).toEqual(
-       new Uint8Array([0x61, 0xed, 0xa3, 0x86, 0x62]));
-   });
-
-   it('allows for stray low surrogates', () => {
-     const arrayBuffer = encode(String.fromCharCode(0x61, 0xde19, 0x62));
-     expect(new Uint8Array(arrayBuffer)).toEqual(
-       new Uint8Array([0x61, 0xed, 0xb8, 0x99, 0x62]));
-   });
-});

Libraries/Utilities/utf8.js

@@ -1,91 +0,0 @@
-/**
- * Copyright (c) 2016-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule utf8
- * @flow
- */
-'use strict';
-
-class ByteVector {
-  _storage: Uint8Array;
-  _sizeWritten: number;
-
-  constructor(size) {
-    this._storage = new Uint8Array(size);
-    this._sizeWritten = 0;
-  }
-
-  push(value: number): ByteVector {
-    const i = this._sizeWritten;
-    if (i === this._storage.length) {
-      this._realloc();
-    }
-    this._storage[i] = value;
-    this._sizeWritten = i + 1;
-    return this;
-  }
-
-  getBuffer(): ArrayBuffer {
-    return this._storage.buffer.slice(0, this._sizeWritten);
-  }
-
-  _realloc() {
-    const storage = this._storage;
-    this._storage = new Uint8Array(align(storage.length * 1.5));
-    this._storage.set(storage);
-  }
-}
-
-/*eslint-disable no-bitwise */
-exports.encode = (string: string): ArrayBuffer => {
-  const {length} = string;
-  const bytes = new ByteVector(length);
-
-  // each character / char code is assumed to represent an UTF-16 wchar.
-  // With the notable exception of surrogate pairs, each wchar represents the
-  // corresponding unicode code point.
-  // For an explanation of UTF-8 encoding, read [1]
-  // For an explanation of UTF-16 surrogate pairs, read [2]
-  //
-  // [1] https://en.wikipedia.org/wiki/UTF-8#Description
-  // [2] https://en.wikipedia.org/wiki/UTF-16#U.2B10000_to_U.2B10FFFF
-  let nextCodePoint = string.charCodeAt(0);
-  for (let i = 0; i < length; i++) {
-    let codePoint = nextCodePoint;
-    nextCodePoint = string.charCodeAt(i + 1);
-
-    if (codePoint < 0x80) {
-      bytes.push(codePoint);
-    } else if (codePoint < 0x800) {
-      bytes
-        .push(0xc0 | codePoint >>> 6)
-        .push(0x80 | codePoint & 0x3f);
-    } else if (codePoint >>> 10 === 0x36 && nextCodePoint >>> 10 === 0x37) { // high surrogate & low surrogate
-      codePoint = 0x10000 + (((codePoint & 0x3ff) << 10) | (nextCodePoint & 0x3ff));
-      bytes
-        .push(0xf0 | codePoint >>> 18 & 0x7)
-        .push(0x80 | codePoint >>> 12 & 0x3f)
-        .push(0x80 | codePoint >>> 6  & 0x3f)
-        .push(0x80 | codePoint & 0x3f);
-
-      i += 1;
-      nextCodePoint = string.charCodeAt(i + 1);
-    } else {
-      bytes
-        .push(0xe0 | codePoint >>> 12)
-        .push(0x80 | codePoint >>> 6 & 0x3f)
-        .push(0x80 | codePoint & 0x3f);
-    }
-  }
-  return bytes.getBuffer();
-};
-
-// align to multiples of 8 bytes
-function align(size: number): number {
-  return size % 8 ? (Math.floor(size / 8) + 1) << 3 : size;
-}