MSE: Update WebM test metadata to match cumulative result of WebM stream parser frame duration estimations

Chromium r264708 modified the WebMStreamParser's frame duration
estimation logic to use the minimum frame duration seen so far for the
track (if any), rather than the maximum. This change aligns the
corresponding WebM MSE layout test metadata to the previous change, and
should enable the flakiness dashboard (for non-Android) to return to, at
worst, flaky fail (bug 284782) instead of current 100% failure for the
mediasource-duration.html layout test.

BUG=375927
R=acolwell@chromium.org
TEST=mediasource-duration.html passes, no other mediasource layout test regression locally on Linux

Review URL: https://codereview.chromium.org/288343011

git-svn-id: svn://svn.chromium.org/blink/trunk@174532 bbb929c8-8fbe-4397-9dbb-9b2b20218538
LeakExpectation: Add expectations for inspector leaks

The list is based on https://storage.googleapis.com/chromium-layout-test-archives/WebKit_Linux_Leak/1244/layout-test-results/results.html

NOTRY=true
BUG=376188, 364408
R=kouhei@chromium.org

Review URL: https://codereview.chromium.org/296153004

git-svn-id: svn://svn.chromium.org/blink/trunk@174533 bbb929c8-8fbe-4397-9dbb-9b2b20218538