Initial version of nativeCSSDetect() - only accepts a string e.g. '(flex-wrap:reverse)'; would quite like to overload the interface

src/nativeCSSDetect.js

@@ -0,0 +1,25 @@
+define(['injectElementWithStyles'], function ( injectElementWithStyles ) {
+    // Function to allow us to use native feature detection functionality if available.
+    // Only accepts the string notation, i.e.: `nativeCSSDetect('(display:flex)')`, not
+    // `nativeCSSDetect('display', 'flex')`
+    function nativeCSSDetect ( str ) {
+        // Start with the W3C version: http://www.w3.org/TR/css3-conditional/#the-css-interface
+        if ('CSS' in window && 'supports' in window.CSS) {
+            return window.CSS.supports(str);
+        }
+        // Otherwise fall back to the at-rule for Opera: they made a bit of a hash of
+        // `window.CSS.supports()`, by implementing it as `window.supportsCSS()` which
+        // only supported f(property, value) calls rather than f(conditionText)
+        else if ('CSSSupportsRule' in window) {
+            return injectElementWithStyles('@supports ' + str + ' { #modernizr { position: absolute; } }', function( node ) {
+                return (window.getComputedStyle ?
+                        getComputedStyle(node, null) :
+                        node.currentStyle)['position'] == 'absolute';
+            });
+        }
+        else {
+            return undefined;
+        }
+    }
+    return nativeCSSDetect;
+});