Don't server / request the Cached resource for if its Main resource is explicitly cancelled

1. BrowserEngine.load("www.test1.com");
2. loadworker1 is still RUNNING
3. BrowserEngine.load("www.test2.com");
4. Loadworker1 == Cancel && Loadworker 2 == RUNNING

Some of the pending cached scripts (Image, CSS, Scripts) which are async load or pending load (resource which are updated from css or from delayed JavaScript load) are loaded for test1.com even after test2.com is loading.