Web Inspector: Allow toolbar customization

Web Inspector: Allow toolbar customization
https://bugs.webkit.org/show_bug.cgi?id=112440

Adds a tools menu item that allows the user to show/hide
inspector panels on the toolbar.

Patch by Alexei Filippov <alph@chromium.org> on 2013-03-20
Reviewed by Yury Semikhatsky.

* inspector/front-end/InspectorView.js:
* inspector/front-end/Settings.js:
(WebInspector.Settings):
(WebInspector.ExperimentsSettings):
* inspector/front-end/Toolbar.js:
(WebInspector.Toolbar):
(WebInspector.Toolbar.prototype.addPanel):
(WebInspector.Toolbar.prototype._isPanelVisibleByDefault):
(WebInspector.Toolbar.prototype.set _hidePanel):
(WebInspector.Toolbar.prototype._showPanel):
(WebInspector.Toolbar.prototype._togglePanelsMenu):
* inspector/front-end/inspector.css:
(#toolbar-panels-menu):
(#toolbar-panels-menu:hover):
(#toolbar-panels-menu:active):
* inspector/front-end/inspector.html:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@146319 268f45cc-cd09-0410-ab3c-d52691b4dbfc