Bug 1071878 - Put an empty rectangle for websites without favicons on new tablet. r=lucasr

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rename : mobile/android/base/resources/drawable-large-hdpi-v11/favicon_none.png => mobile/android/base/resources/drawable-large-hdpi-v11/new_tablet_default_favicon.png
rename : mobile/android/base/resources/drawable-large-mdpi-v11/favicon_none.png => mobile/android/base/resources/drawable-large-mdpi-v11/new_tablet_default_favicon.png
rename : mobile/android/base/resources/drawable-large-xhdpi-v11/favicon_none.png => mobile/android/base/resources/drawable-large-xhdpi-v11/new_tablet_default_favicon.png
rename : mobile/android/base/resources/drawable-large-xxhdpi-v11/favicon_none.png => mobile/android/base/resources/drawable-large-xxhdpi-v11/new_tablet_default_favicon.png