[Android WebView] Fix non-wide viewport handling code after r157293

For pages lacking <meta viewport>, page scale boundaries passed to
PageScaleConstraintsSet::adjustForAndroidWebViewQuirks will be [-1, -1],
not [0.25, 5] as we used to.

BUG=332931

Review URL: https://codereview.chromium.org/131883003

git-svn-id: svn://svn.chromium.org/blink/trunk@164870 bbb929c8-8fbe-4397-9dbb-9b2b20218538