Lazily generate HistoryItem's serialized form state

Source/web/WebFrameImpl.cpp

Index: Source/web/WebFrameImpl.cpp
diff --git a/Source/web/WebFrameImpl.cpp b/Source/web/WebFrameImpl.cpp
index 9c0e5406427d2746a7dd0f57ac2fa64be2409ad1..bf727e76803b4e9c12f6cba294806a3257e0710c 100644
--- a/Source/web/WebFrameImpl.cpp
+++ b/Source/web/WebFrameImpl.cpp
@@ -1005,11 +1005,6 @@ WebHistoryItem WebFrameImpl::currentHistoryItem() const
     // We're shutting down.
     if (!frame()->loader().documentLoader())
         return WebHistoryItem();
-
-    // Lazily update the document state if it was dirtied. Doing it here
-    // avoids synchronously serializing forms as they're changing.
-    frame()->loader().saveDocumentState();

[Nate Chapin, 2014/04/17 21:16:25]

This whole function is already dead as a result of moving history state to
content/renderer.

This call to saveDocumentState() was kind of important for not randomly dropping
form state, hence my timing in writing this patch :)

-
     return WebHistoryItem(frame()->page()->historyController().currentItemForExport());
 }