[DevTools] Escape exclamation points in copy as curl

Bug: 919356
Change-Id: I8b7769f6d6fef258f31dd16367d54b505284a7d8
Reviewed-on: https://chromium-review.googlesource.com/c/1437265
Commit-Queue: Joey Arhar <jarhar@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626211}