wpt: Fix test_driver's minimize/restore functions.

By default the test_driver API calls should be routed to the window
corresponding to the driver. However the minimize/restore calls use the
top level window. Fix this by passing the frame token to look up the
correct WebContents corresponding to the blink Window.

R=danakj@chromium.org

Bug: 1522213
Change-Id: I99ed32cd4d9020d9832c63344fee004a40461148
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5310776


Commit-Queue: Khushal Sagar <khushalsagar@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Auto-Submit: Khushal Sagar <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1263515}