Add assets for Web Inspector Keyboard Shortcuts blog post.
* blog-files/web-inspector-keyboard-shortcuts/clear-console.png: Added.
* blog-files/web-inspector-keyboard-shortcuts/console-filters.m4v: Added.
* blog-files/web-inspector-keyboard-shortcuts/debugger-shortcuts.png: Added.
* blog-files/web-inspector-keyboard-shortcuts/hide-element.m4v: Added.
* blog-files/web-inspector-keyboard-shortcuts/select-next-and-previous-tabs.m4v: Added.
* blog-files/web-inspector-keyboard-shortcuts/toggle-split-console.m4v: Added.
* blog-files/web-inspector-keyboard-shortcuts/tooltips.gif: Added.
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@190598
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