(split)Sheets management for css() (cssinjs#1137)

* initial verion of css innterface

* use string based cache, which can be optimized later with a babel plugin

* merge labels

* support arrays

* check cache early

* implement composition

* add flow types [ci skip]

* fix tests, export types

* Update packages/css-jss/src/index.js

use createCss directly

Co-Authored-By: Henri <henribeck.dev@gmail.com>

* cr changes

* dedupe labels

* changelog

* revert browsers.json changes

* create new sheets when rules amount is too high

* changelog

.size-snapshot.json

@@ -1,13 +1,13 @@
 {
   "dist/react-jss.js": {
-    "bundled": 167824,
-    "minified": 58073,
-    "gzipped": 18921
+    "bundled": 168182,
+    "minified": 58162,
+    "gzipped": 18963
   },
   "dist/react-jss.min.js": {
-    "bundled": 111099,
-    "minified": 41427,
-    "gzipped": 13983
+    "bundled": 111457,
+    "minified": 41516,
+    "gzipped": 14027
   },
   "dist/react-jss.cjs.js": {
     "bundled": 26174,

src/jsx.test.js

@@ -13,8 +13,8 @@ const jsx = (...args) => currJsx(...args)
 
 describe('React-JSS: jsx', () => {
   beforeEach(() => {
-    const sheet = createJss({createGenerateId}).createStyleSheet()
-    const css = createCss(sheet)
+    const jss = createJss({createGenerateId})
+    const css = createCss(jss)
     currJsx = createJsx(css)
   })