TextAutosizer should handle frames without a FrameView.

During cross-process navigation, it is possible to create a LocalFrame
that doesn't have a FrameView, since the latter gets created at the time
a document commits. Since the commit in this case happens later in time,
the current code crashes as it expects the view to be there.

BUG=357747

Review URL: https://codereview.chromium.org/1374783005

Cr-Commit-Position: refs/heads/master@{#351204}

third_party/WebKit/Source/core/layout/TextAutosizer.cpp

@@ -532,6 +532,9 @@ void TextAutosizer::updatePageInfo()
             return;
 
         LocalFrame* mainFrame = m_document->page()->deprecatedLocalMainFrame();
+        if (!mainFrame->view())
+            return;
+
         IntSize frameSize = m_document->settings()->textAutosizingWindowSizeOverride();
         if (frameSize.isEmpty())
             frameSize = windowSize();