Remove react native bundles for core and cache in favour of different…

… isBrowser detection (#1482)

.changeset/popular-mayflies-sell/changes.json

@@ -0,0 +1,7 @@
+{
+  "releases": [
+    { "name": "@emotion/cache", "type": "patch" },
+    { "name": "@emotion/core", "type": "patch" }
+  ],
+  "dependents": []
+}

.changeset/popular-mayflies-sell/changes.md

@@ -0,0 +1 @@
+Remove react native bundles in favour of different isBrowser detection

packages/cache/package.json

@@ -8,14 +8,6 @@
     "./dist/cache.cjs.js": "./dist/cache.browser.cjs.js",
     "./dist/cache.esm.js": "./dist/cache.browser.esm.js"
   },
-  "react-native": {
-    "./dist/cache.cjs.js": "./dist/cache.native.cjs.js",
-    "./dist/cache.esm.js": "./dist/cache.native.esm.js"
-  },
-  "sketch": {
-    "./dist/cache.cjs.js": "./dist/cache.native.cjs.js",
-    "./dist/cache.esm.js": "./dist/cache.native.esm.js"
-  },
   "types": "types/index.d.ts",
   "license": "MIT",
   "repository": "https://github.com/emotion-js/emotion/tree/master/packages/cache",

packages/core/package.json

@@ -7,14 +7,6 @@
     "./dist/core.cjs.js": "./dist/core.browser.cjs.js",
     "./dist/core.esm.js": "./dist/core.browser.esm.js"
   },
-  "react-native": {
-    "./dist/core.cjs.js": "./dist/core.native.cjs.js",
-    "./dist/core.esm.js": "./dist/core.native.esm.js"
-  },
-  "sketch": {
-    "./dist/core.cjs.js": "./dist/core.native.cjs.js",
-    "./dist/core.esm.js": "./dist/core.native.esm.js"
-  },
   "types": "types/index.d.ts",
   "files": [
     "src",

packages/core/src/context.js

@@ -5,7 +5,13 @@ import createCache from '@emotion/cache'
 import { isBrowser } from './utils'
 
 let EmotionCacheContext: React.Context<EmotionCache | null> = React.createContext(
-  isBrowser ? createCache() : null
+  // we're doing this to avoid preconstruct's dead code elimination in this one case
+  // because this module is primarily intended for the browser and node
+  // but it's also required in react native and similar environments sometimes
+  // and we could have a special build just for that
+  // but this is much easier and the native packages
+  // might use a different theme context in the future anyway
+  typeof HTMLElement !== 'undefined' ? createCache() : null
 )
 
 export let ThemeContext = React.createContext<Object>({})