Optimize chrome://inspect for small windows
Optimize chrome://inspect for small windows

The body's min-width was set to 47em (consistent with other Chrome UI
pages). This patch removes the scrollbars in the navigation and content
when the window becomes smaller than 47em. The sidebar will then no
longer appear to be at a fixed location, but in a small window there is
not much screen estate, so this is ok.

BUG=507181
R=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/1220043004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#337773}

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