Move more WebMIDI to oilpan.

WebMIDIPermissionRequest::WebMIDIPermissionRequest(WebCore::MIDIAccess* midi) was removed to resolve compile-time ambiguity when oilpan is enabled. This also align with other WebPrivatePtr wrapper classes.

BUG=340522

Review URL: https://codereview.chromium.org/179113003

git-svn-id: svn://svn.chromium.org/blink/trunk@167746 bbb929c8-8fbe-4397-9dbb-9b2b20218538