[Android] Upstream WebCore/history/android: Require some platform specific state attached to HistoryItem.
https://bugs.webkit.org/show_bug.cgi?id=31913

Reviewed by Brady Eidson.

Android stores information such as the zoom scale factor and bridge back to the Java counterpart with HistoryItem.

No new tests required as this is Android specific code.

* history/HistoryItem.h: Add Android specific member data to HistoryItem.
* history/android: Added.
* history/android/AndroidWebHistoryBridge.h: Added.
* history/android/HistoryItemAndroid.cpp: Added, provides implementation for Android specific member functions in HistoryItem.
(WebCore::HistoryItem::bridge): Added.
(WebCore::HistoryItem::setBridge): Added.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@51628 268f45cc-cd09-0410-ab3c-d52691b4dbfc