This code was previously relying on the PageView::on_load_start hook
firing synchronously when calling PageView::load(). This was not
happening with WebContentView, so it broke the back/forward history.
Instead, we now differentiate between history navigations and normal
loads in Tab::load(). History navigations don't push new entries into
history, but instead just move the history pointer.
The JavaScript console can be opened with Control+I, or using
the menu option. The console is currently a text box with JS
syntax highlighting which will send commands to the document's
interpreter. All output is printed to an HTML view in the console.
The output is an HtmlView to easily allow complex output, such
as expandable views for JS Objects in the long run.
