Factor out GamepadCommon base class from Gamepad and WebKitGamepad

Source/modules/gamepad/WebKitGamepadList.cpp

Index: Source/modules/gamepad/WebKitGamepadList.cpp
diff --git a/Source/modules/gamepad/WebKitGamepadList.cpp b/Source/modules/gamepad/WebKitGamepadList.cpp
index da3cec035cfa7c6f3c9422ced08e90c92eb9dedf..a06a11f819017bbc7bf09fc15fad965b1735ad2c 100644
--- a/Source/modules/gamepad/WebKitGamepadList.cpp
+++ b/Source/modules/gamepad/WebKitGamepadList.cpp
@@ -7,10 +7,6 @@
 
 namespace WebCore {
 
-WebKitGamepadList::~WebKitGamepadList()
-{
-}
-
 void WebKitGamepadList::set(unsigned index, PassRefPtrWillBeRawPtr<WebKitGamepad> gamepad)
 {
     if (index >= blink::WebGamepads::itemsLengthCap)
@@ -18,11 +14,6 @@ void WebKitGamepadList::set(unsigned index, PassRefPtrWillBeRawPtr<WebKitGamepad
     m_items[index] = gamepad;
 }
 
-unsigned WebKitGamepadList::length() const
-{
-    return blink::WebGamepads::itemsLengthCap;
-}
-
 WebKitGamepad* WebKitGamepadList::item(unsigned index)
 {
     return index < length() ? m_items[index].get() : 0;