Don't reuse HistoryItems for multiple navigations

Source/web/tests/ProgrammaticScrollTest.cpp

 #include "config.h"
 
 #include "core/frame/FrameView.h"
 #include "core/layout/LayoutView.h"
 #include "platform/testing/URLTestHelpers.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebUnitTestSupport.h"
 #include "public/web/WebFrame.h"
 #include "public/web/WebFrameClient.h"
 #include "public/web/WebHistoryItem.h"
@@ skipping 74 matching lines @@
     webView->resize(WebSize(1000, 1000));
     webView->layout();
 
     WebViewImpl* webViewImpl = toWebViewImpl(webView);
     LocalFrame* frame = webViewImpl->mainFrameImpl()->frame();
     frame->loader().setLoadType(FrameLoadTypeBackForward);
 
     webViewImpl->setPageScaleFactor(3.0f);
     webViewImpl->setMainFrameScrollOffset(WebPoint(0, 500));
     frame->view()->setWasScrolledByUser(false);
-    frame->loader().currentItem()->setPageScaleFactor(0);
+    frame->loader().currentItem()->setPageScaleFactor(1.0f);
     frame->loader().currentItem()->setScrollPoint(WebPoint(0, 400));
 
-    // FrameLoader::restoreScrollPositionAndViewState flows differently if scale is zero.
+    // FrameLoader::restoreScrollPositionAndViewState flows differently if scale is 1.
     frame->loader().restoreScrollPositionAndViewState();
 
     // Expect that only the scroll position was restored.
     EXPECT_EQ(3.0f, webViewImpl->pageScaleFactor());
     EXPECT_EQ(400, webViewImpl->mainFrameImpl()->scrollOffset().height);
 }
 
 }