Stop checking for executable binaries on windows

It's apparently not as reliable as we thought, and it also doesn't
really seem to matter whether or not perl thinks the binary we found is
executable.

lib/Selenium/CanStartBinary/FindBinary.pm

@@ -11,6 +11,8 @@ require Exporter;
 our @ISA = qw/Exporter/;
 our @EXPORT_OK = qw/coerce_simple_binary coerce_firefox_binary/;
 
+use constant IS_WIN => $^O eq 'MSWin32';
+
 sub coerce_simple_binary {
     my ($executable) = @_;
 
@@ -45,7 +47,7 @@ sub _validate_manual_binary {
     };
 
     if ( $abs_executable ) {
-        if ( -x $abs_executable ) {
+        if ( -x $abs_executable || IS_WIN ) {
             return $abs_executable;
         }
         else {