Refactor frame navigation/detach state cleanup to be more sane.

Source/web/tests/PinchViewportTest.cpp

Index: Source/web/tests/PinchViewportTest.cpp
diff --git a/Source/web/tests/PinchViewportTest.cpp b/Source/web/tests/PinchViewportTest.cpp
index bdda29f434c3b1a0a5a681d81ccf81430bcc19a3..efaf9b35f36f56573ce191d9e5720c1b12914e1c 100644
--- a/Source/web/tests/PinchViewportTest.cpp
+++ b/Source/web/tests/PinchViewportTest.cpp
@@ -1547,6 +1547,9 @@ TEST_F(PinchViewportTest, TestMainFrameInitializationSizing)
     navigateTo(m_baseURL + "content-width-1000-min-scale.html");
 
     WebLocalFrameImpl* localFrame = webViewImpl()->mainFrameImpl();
+    // This is a hack to prevent createFrameView() from violating invariants
+    // about frame state during navigation/detach.
+    localFrame->frame()->document()->prepareForDestruction();

[dcheng, 2015/04/03 14:35:45]

I couldn't think of a good way to adapt this test without having to understand
frame detach/navigation internals. So I just hacked around it for now. I plan on
revisiting this later.

     localFrame->createFrameView();
 
     FrameView& frameView = *localFrame->frameView();