Enable CSS grid layout in test_shell to ease development.

webkit/tools/test_shell/webview_host_gtk.cc

Index: webkit/tools/test_shell/webview_host_gtk.cc
diff --git a/webkit/tools/test_shell/webview_host_gtk.cc b/webkit/tools/test_shell/webview_host_gtk.cc
index 40b61fafcaf0b6c95c098f047c09089096429ff1..117da8915dca2017730ef80381229353b23add6c 100644
--- a/webkit/tools/test_shell/webview_host_gtk.cc
+++ b/webkit/tools/test_shell/webview_host_gtk.cc
@@ -8,6 +8,7 @@
 
 #include "base/logging.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebSettings.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 #include "webkit/glue/webpreferences.h"
@@ -30,6 +31,7 @@ WebViewHost* WebViewHost::Create(GtkWidget* parent_view,
   host->webwidget_ = WebView::create(delegate);
   host->webview()->setDevToolsAgentClient(dev_tools_client);
   prefs.Apply(host->webview());
+  host->webview()->settings()->setExperimentalCSSGridLayoutEnabled(true);
   host->webview()->initializeMainFrame(delegate);
   host->webwidget_->layout();