Summary: Back/forward keyboard shortcut stops working after first use. Steps to Reproduce: 1. Inspect a page with multiple source files 2. Open Debugger tab 3. Select some items in the sidebar to build up the back/forward history 4. Focus the source view, then navigate backwards by pressing ⌃⌘← => Navigates to previous source file 6. Repeat ⌃⌘← => Nothing happens, even though the source view appears to have the focus
<rdar://problem/37623173>