Minor cleanups for FirefoxDriver.java (#2129)

Minor cleanups for FirefoxDriver.java.

- Do not use System.out in production code.
- Omit null check of marionette as it is redundant with the instanceof check.

java/client/src/org/openqa/selenium/firefox/FirefoxDriver.java

@@ -130,13 +130,11 @@ public FirefoxDriver(FirefoxProfile profile) {
   public FirefoxDriver(Capabilities desiredCapabilities) {
     this(getBinary(desiredCapabilities), extractProfile(desiredCapabilities, null),
         desiredCapabilities);
-    System.out.println("FirefoxDriver " + desiredCapabilities);
   }
 
   public FirefoxDriver(Capabilities desiredCapabilities, Capabilities requiredCapabilities) {
     this(getBinary(desiredCapabilities), extractProfile(desiredCapabilities, requiredCapabilities),
         desiredCapabilities, requiredCapabilities);
-    System.out.println("FirefoxDriver " + desiredCapabilities + " " + requiredCapabilities);
   }
 
   private static FirefoxProfile extractProfile(Capabilities desiredCapabilities,
@@ -228,7 +226,7 @@ private static final CommandExecutor createCommandExecutor(Capabilities desiredC
                                                              FirefoxBinary binary,
                                                              FirefoxProfile profile) {
     Object marionette = desiredCapabilities.getCapability(MARIONETTE);
-    if (marionette != null && marionette instanceof Boolean && !(Boolean) marionette) {
+    if (marionette instanceof Boolean && !(Boolean) marionette) {
       return new LazyCommandExecutor(binary, profile);
     } else {
       GeckoDriverService.Builder builder = new GeckoDriverService.Builder();