Add a force-layout-height-to-zero layout mode to WebViewImpl

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index f4e161c00ad670a1bc8f27728e1f3aa15c9dd9c8..cee9430fd72ec8f52fb9d520ee366f2b40f66f49 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -3049,6 +3049,9 @@ void WebViewImpl::updateMainFrameLayoutSize()
         }
     }
 
+    if (page()->settings().forceZeroLayoutHeight())
+        layoutSize.height = 0;

[abarth-chromium, 2014/07/29 16:54:55]

The settings machinery looks fine, but I don't understand the consequences of
this part of the CL.  We'll need to get someone who understands this line to
complete the review.

[mkosiba (inactive), 2014/07/29 16:57:43]

Thanks! I'll ask Alex to take a look.

+
     view->setLayoutSize(layoutSize);
 }