Reset multipliers correctly when autosizing is turned off.

This lets us re-land http://crrev.com/208393008 without breaking
AwSettingsTest.testLayoutAlgorithmWithTwoViews.

Without http://crrev.com/208393008, style recalc would always reset the
autosizing multiplier to 1, so the bug in recalculateMultipliers was not
noticed.

BUG=353309,356960

Review URL: https://codereview.chromium.org/215063004

git-svn-id: svn://svn.chromium.org/blink/trunk@170241 bbb929c8-8fbe-4397-9dbb-9b2b20218538