Fix bug: when pageYOffset is not zero,the first time animate scrolling will got an error.

Author: dingyi1993

src/js/smooth-scroll/smooth-scroll.js

@@ -273,7 +273,7 @@
 
 		// Get the hash to use
 		var hash = window.location.hash;
-		hash = hash ? hash : window.pageYOffset;
+		hash = hash ? hash : '';
 
 		// Set a default history
 		history.replaceState(
@@ -542,7 +542,7 @@
 
 			// Get the anchor
 			var anchor = history.state.anchor;
-			if (anchor && anchor !== 0) {
+			if (typeof anchor === 'string' && anchor) {
 				anchor = document.querySelector(escapeCharacters(history.state.anchor));
 				if (!anchor) return;
 			}