[DevTools] Input.emulateTouchFromMouseEvent API.
[DevTools] Input.emulateTouchFromMouseEvent API.

BUG=384522

Review URL: https://codereview.chromium.org/405113004

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@178844 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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