Fix issue 8254: Extensions were incorrectly transferred between Windows client and Linux grid node, because ZipEntry had incorrect name with '\' as separators.

------
Note from Kristian: This patch is is line with section 4.4.17 of the Zip specifications.
Heavens knows what that java.util.Zip designers were doing when they did not build
this into the library.

Author: tporeba

java/client/src/org/openqa/selenium/io/Zip.java

@@ -103,7 +103,7 @@ private void addToZip(String basePath, ZipOutputStream zos, File toAdd) throws I
       FileInputStream fis = new FileInputStream(toAdd);
       String name = toAdd.getAbsolutePath().substring(basePath.length() + 1);
 
-      ZipEntry entry = new ZipEntry(name);
+      ZipEntry entry = new ZipEntry(name.replace('\\', '/'));
       zos.putNextEntry(entry);
 
       int len;