allow ssr with global

Co-authored-by: Austin Buckler <buckleraustin@gmail.com>

packages/splitjs/src/split.js

@@ -2,8 +2,9 @@
 // maintainable code, while at the same time manually optimizing for tiny minified file size,
 // browser compatibility without additional requirements
 // and very few assumptions about the user's page layout.
-const global = window
-const { document } = global
+const global = typeof window !== 'undefined' ? window : null
+const ssr = global === null
+const document = !ssr ? global.document : undefined
 
 // Save a couple long function names that are used frequently.
 // This optimization saves around 400 bytes.
@@ -21,7 +22,9 @@ const NOOP = () => false
 //
 // Tests -webkit, -moz and -o prefixes. Modified from StackOverflow:
 // http://stackoverflow.com/questions/16625140/js-feature-detection-to-detect-the-usage-of-webkit-calc-over-calc/16625167#16625167
-const calc = `${['', '-webkit-', '-moz-', '-o-']
+const calc = ssr
+    ? 'calc'
+    : `${['', '-webkit-', '-moz-', '-o-']
           .filter(prefix => {
               const el = document.createElement('div')
               el.style.cssText = `width:${prefix}calc(9px)`
@@ -126,6 +129,8 @@ const defaultGutterStyleFn = (dim, gutSize) => ({ [dim]: `${gutSize}px` })
 //    `pair` object and a gutter.
 // 5. Actually size the pair elements, insert gutters and attach event listeners.
 const Split = (idsOption, options = {}) => {
+    if (ssr) return {}
+
     let ids = idsOption
     let dimension
     let clientAxis