VersionResourceResolver should delegate to the chain

Prior to this commit, the `VersionResourceResolver` implementations of
`resolveUrlPathInternal` would delegate to the resolver chain but would
never use the give result if the current request didn't match a
configured version strategy pattern.

This is a problem if the resolver supposed to resolve the resource path
is configured after a `VersionResourceResolver` in the resolver chain;
this means that other resolver never gets to participate in the result
of the chain.

Issue: SPR-15372

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -206,7 +206,7 @@ public class VersionResourceResolver extends AbstractResourceResolver {
 		if (StringUtils.hasText(baseUrl)) {
 			VersionStrategy versionStrategy = getStrategyForPath(resourceUrlPath);
 			if (versionStrategy == null) {
-				return null;
+				return baseUrl;
 			}
 			if (logger.isTraceEnabled()) {
 				logger.trace("Getting the original resource to determine version for path \"" + resourceUrlPath + "\"");