[fix] unitless values for vendor prefixed properties

Problem:

Numeric values are suffixed with 'px', unless the property supports
unitless values. However, vendor prefixed properties were ignored
resulting in invalid CSS values for properties like
'-webkit-flex-shrink'.

Solution:

Apply the upstream solution from React, which includes vendor prefixed
properties in the "unitless number" map. Also build a custom vendor
prefixer to ensure adequate browser support (i.e., Safari 7 and older
Chrome).

scripts/createPrefixer.js

@@ -0,0 +1,21 @@
+const generateData = require('inline-style-prefixer/generator');
+const path = require('path');
+
+const browserList = {
+  chrome: 38,
+  android: 4,
+  firefox: 40,
+  ios_saf: 7,
+  safari: 7,
+  ie: 11,
+  ie_mob: 11,
+  edge: 12,
+  opera: 16,
+  op_mini: 12,
+  and_uc: 9,
+  and_chr: 38
+};
+
+generateData(browserList, {
+  staticPath: path.join(__dirname, '../src/modules/prefixStyles/static.js'),
+});