split emoji support methods from the async module

app/assets/javascripts/behaviors/gl_emoji.js

 import installCustomElements from 'document-register-element';
-import { emojiMap, normalizeEmojiName, isEmojiUnicodeSupported, getUnicodeSupportMap } from '../emoji';
+import { emojiMap, normalizeEmojiName } from '../emoji';
+import isEmojiUnicodeSupported from '../emoji/support';
 
 installCustomElements(window);
 
-const generatedUnicodeSupportMap = getUnicodeSupportMap();
-
 function emojiImageTag(name, src) {
   return `<img class="emoji" title=":${name}:" alt=":${name}:" src="${src}" width="20" height="20" align="absmiddle" />`;
 }
@@ -82,7 +81,7 @@ function installGlEmojiElement() {
     if (
       emojiUnicode &&
       isEmojiUnicode &&
-      !isEmojiUnicodeSupported(generatedUnicodeSupportMap, emojiUnicode, unicodeVersion)
+      !isEmojiUnicodeSupported(emojiUnicode, unicodeVersion)
     ) {
       // CSS sprite fallback takes precedence over image fallback
       if (hasCssSpriteFalback) {
@@ -106,5 +105,4 @@ function installGlEmojiElement() {
 export {
   installGlEmojiElement,
   glEmojiTag,
-  emojiImageTag,
 };

app/assets/javascripts/emoji/index.js

 import emojiMap from 'emojis/digests.json';
 import emojiAliases from 'emojis/aliases.json';
-import getUnicodeSupportMap from './unicode_support_map';
-import isEmojiUnicodeSupported from './is_emoji_unicode_supported';
 
 const validEmojiNames = [...Object.keys(emojiMap), ...Object.keys(emojiAliases)];
 
@@ -52,8 +50,6 @@ export {
   filterEmojiNames,
   filterEmojiNamesByAlias,
   getEmojiByCategory,
-  getUnicodeSupportMap,
   isEmojiNameValid,
-  isEmojiUnicodeSupported,
   validEmojiNames,
 };

app/assets/javascripts/emoji/support/index.js

+import isEmojiUnicodeSupported from './is_emoji_unicode_supported';
+import getUnicodeSupportMap from './unicode_support_map';
+
+// cache browser support map between calls
+let browserUnicodeSupportMap;
+
+export default function isEmojiUnicodeSupportedByBrowser(emojiUnicode, unicodeVersion) {
+  browserUnicodeSupportMap = browserUnicodeSupportMap || getUnicodeSupportMap();
+  return isEmojiUnicodeSupported(browserUnicodeSupportMap, emojiUnicode, unicodeVersion);
+}

app/assets/javascripts/emoji/unicode_support_map.js → app/assets/javascripts/emoji/support/unicode_support_map.js

-import AccessorUtilities from '../lib/utils/accessor';
+import AccessorUtilities from '../../lib/utils/accessor';
 
 const unicodeSupportTestMap = {
   // man, student (emojione does not have any of these yet), http://emojipedia.org/emoji-zwj-sequences/

spec/javascripts/behaviors/gl_emoji/unicode_support_map_spec.js

-import getUnicodeSupportMap from '~/emoji/unicode_support_map';
+import getUnicodeSupportMap from '~/emoji/support/unicode_support_map';
 import AccessorUtilities from '~/lib/utils/accessor';
 
 describe('Unicode Support Map', () => {

spec/javascripts/gl_emoji_spec.js

@@ -5,7 +5,7 @@ import isEmojiUnicodeSupported, {
   isSkinToneComboEmoji,
   isHorceRacingSkinToneComboEmoji,
   isPersonZwjEmoji,
-} from '~/emoji/is_emoji_unicode_supported';
+} from '~/emoji/support/is_emoji_unicode_supported';
 
 const emptySupportMap = {
   personZwj: false,