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..25c1be74dce5fa2b6b576da0cbd3637b62953309 100644
--- a/Source/web/tests/PinchViewportTest.cpp
+++ b/Source/web/tests/PinchViewportTest.cpp
@@ -1547,10 +1547,15 @@ TEST_F(PinchViewportTest, TestMainFrameInitializationSizing)
     navigateTo(m_baseURL + "content-width-1000-min-scale.html");
 
     WebLocalFrameImpl* localFrame = webViewImpl()->mainFrameImpl();
+    // The prepareForDestruction() and prepareForDetach() calls are a hack to
+    // prevent createView() from violating invariants about frame state during
+    // navigation/detach.
+    localFrame->frame()->document()->prepareForDestruction();
     localFrame->createFrameView();
 
     FrameView& frameView = *localFrame->frameView();
     EXPECT_SIZE_EQ(IntSize(200, 400), frameView.frameRect().size());
+    frameView.prepareForDetach();
 }
 
 // Tests that the maximum scroll offset of the viewport can be fractional.