fix(addStyles): update for test for old IE versions (#196)

addStyles.js

@@ -11,7 +11,12 @@ var stylesInDom = {},
 		};
 	},
 	isOldIE = memoize(function() {
-		return /msie [6-9]\b/.test(self.navigator.userAgent.toLowerCase());
+		// Test for IE <= 9 as proposed by Browserhacks
+		// @see http://browserhacks.com/#hack-e71d8692f65334173fee715c222cb805
+		// Tests for existence of standard globals is to allow style-loader 
+		// to operate correctly into non-standard environments
+		// @see https://github.com/webpack-contrib/style-loader/issues/177
+		return window && document && document.all && !window.atob;
 	}),
 	getElement = (function(fn) {
 		var memo = {};